I have my new CP88 connected to Soundmondo all ready to Sync (screenshot1). So I visit a page of a sound with an interesting title... (screenshot2) but how do I hear it?

Click on SYNC. The selected program is bulked to your instrument.

I press Sync, and it takes me to a page which invites me to enter a Title for the sound, tags etc, make it Public or Private (screenshot3).

At this time you should be playing the sound that has been transferred to your CP88. You have completed the task of transferring the sound you have selected to your CP88. It is in the instrument’s Edit Buffer. This means it has not overwritten anything in your instrument yet, it is available for you to play, explore, edit if you so desire.

If you wish to keep this sound, press the [STORE] button on the CP88 and direct it to one of your on board memory locations.
If you do not wish to keep this sound, simply change your selection on the CP88 and it will disappear.

If you don’t want to keep the sound in your CP88 but wish to store it on your computer, then on your computer click SAVE (mark “Private” ) this will keep it in your Soundmondo area on your local computer.

If you make what you think are improvements that you wish to share with others, give your new version a NAME, and add a description about what you’ve changed and perhaps why you see this as an improvement. We also encourage users to create a SoundCloud or YouTube video of yourself performing your creation.

DO NOT just repost someone else’s program by clicking SAVE PUBLIC — you will be taking credit for their work (how rude). If you did not make any improvements that you want to share, don’t Save as PUBLIC. Many do this by mistake because they don’t realize that when you click SYNC, the data you requested is immediately transferred via MIDI BULK DUMP to your CP88. At that point, look away from the computer, PLAY the program on the CP88...

You only need to deal with the computer again if you want to SAVE on your computer for later (PRIVATE).
Click on the gear to the right of the SEARCH field (top right) in order to view your PRIVATE collection (and all the items you’ve shared).

When it does not respond, look for error messages (red x), solve the error... you may see that you are attempting to load or run an unidentified/unknown script (which to your computer, the bulk dump might very well appear that way)... click on the error icon and “Allow”.

Hope that helps

Thanks for your reply, it's much appreciated. But it does seem that something is not working as intended, for me. I can't figure out why not.
Your advice is exactly as I 'expected' it to work. You said:

Click on SYNC. The selected program is bulked to your instrument.
At this time you should be playing the sound that has been transferred to your CP88. You have completed the task of transferring the sound you have selected to your CP88. It is in the instrument’s Edit Buffer. This means it has not overwritten anything in your instrument yet, it is available for you to play, explore, edit if you so desire.

So I've just carefully repeated this process again. Here's what's happening for me, step by step:

The CP88 is powered down. I navigate to the Soundmondo website, and am automatically logged in. The green 'Connected' button is showing - that seems strange...? The Sync button is greyed out and the 'No Entry' sign shows when I hover over it.

I connect the USB cable between the CP88 and the computer, and power up the CP88. The stock 1-1 Natural CFX piano is loaded onto the CP88, and can be played, obviously.

I navigate to a Warm Hammond sound in Soundmondo. The Sync button now becomes active.

I press Sync. The button becomes greyed out again (implying that the operation has been completed?) and the page loads inviting me to name, apply tags, make it public/private etc, and Save.

But the CP88 is still playing the stock piano sound. The Hammond sound has not been transferred to the keyboard.

When I have proceeded on to Save the sound (always choosing to make it Private, I get that!) - nothing happens after pressing Save. My personal library of sounds is still empty.

Are you able to offer any suggestions as to what might be wrong, please? Again - thanks for being here.

The plot thickens...
One thing I hadn't done was to reboot the computer... So I did that.
Returning to the Soundmondo website, the button now showed Disconnected.
Connected the USB cable and powered up the CP88. Remained Disconnected (the address bar shows the Midi symbol and shows 'This page has full control of midi devices)
Then after a while the Disconnected button changed to 'InvalidStateError: Platform dependent initialization failed' Googling this text doesn't bring any results...
There are no errors apparent anywhere within the browser window.

So I'm going nowhere, and maybe even backwards...
Thanks.

The CP88 is powered down. I navigate to the Soundmondo website, and am automatically logged in. The green 'Connected' button is showing - that seems strange...?

Not only strange, but you can stop right here. Until we figure out why the program thinks it is connected we cannot advance (all steps beyond this are unnecessary, until we solve this). I assume no other supported product is connected: refaceCP/CS/DX/YC, MONTAGE, MODX... if they are connected, please disconnect them. Let me see if I can duplicate this — this “Connected” button showing should require a ‘handshake’ with a product, we need to find out to what it thinks it is connected.

Thanks for your help. The situation moved on a little, as per my later post above which begins 'The plot thickens...'

Nothing else is connected, as you rightly assume.

Following restarts of the browser and the computer, the button now shows Disconnected when I open Soundmondo.

What I've now ascertained is that the CP88 connects successfully to the computer via USB. I've confirmed this by opening Audio Midi Setup from the Utilities menu, and I can see the CP88 appear when I connect the USB cable (and disappear when it's disconnected).

But the CP88 never connects in Soundmondo. The Disconnected button is red, and stays red. Eventually it disappears altogether and shows InvalidStateError: Platform dependent initialization failed.

I have access to another mac which I intend to try in the next short while (when it arrives here). I'm trying to test each link in the chain. Now that I know my computer is communicating with the CP88 (as above) I'm suspecting the issue might be in my Chrome installation - although no error messages are showing anywhere, and the symbol/message in the address bar tells me the site has full control of MIDI devices. I hope to test this by using a different computer.

Have set up the CP88 with a second, older macbook pro - and it behaves perfectly, exactly as expected. I can Connect, Browse, and Sync sounds without issues. So I'm currently working on the assumption that the problem is with my own computer.

So I have removed Chrome completely, including the Application Support/Google/Chrome folder, and made a new clean install. Before doing/installing anything else into the browser, I tried Soundmondo - and I have the same problem. The CP88 never connects, and eventually I get the error message in place of the Disconnected button.

End of day 2 working on little else but this... Any advice in the light of latest developments gratefully received. Thanks

Have set up the CP88 with a second, older macbook pro - and it behaves perfectly, exactly as expected

The newer Mac is the key. An ‘improvement’ to how it defaults/works concerning web connectivity is probably the issue. How much newer is the new MacBookPro?
I’ll see if I can find something...

Thanks for your attention to this.
My mac isn't 'new' but merely 'newer' than the one we tried yesterday - with some success. Mine is actually 5 years old. It's running 10.14.6 Mojave, I don't like to 'upgrade' to new OS incarnations too quickly because of exactly the kind of problems you rightly highlight - so I haven't gone up to Catalina. The older mac is incapable of running anything past Snow Leopard, or something. But I feel sure many, many people must be using Soundmondo with macs newer than mine.
I'm relieved to know where the problem lies - I guess that's some progress. And that it's not a CP88 hardware issue, which I was fearful of. But it is deeply frustrating. I know there are many and various settings, extras, extensions etc installed within an OS and Chrome which might get in the way of whatever Soundmondo needs to do, but short of reformatting and rebuilding one step at a time, to try to identify the point at which Soundmondo stops working, I can't see a way forward. I've already tried to do just that with Chrome - going further isn't an attractive option. Maybe we'll just invite the old mac round once in a while...:p
As ever, and wisdom or suggestions gratefully received.