It's a zip file. Unzip it and you will get two files: a PDF describing what you got, and an X7L file containing the library.

Put the X7L file on a USB flash drive, insert the flash drive in Montage, load the file using touchscreen commands.

Thanks Michael. I had already unzipped and copied the file onto a flash drive and inserted that in the Montage. But once it's in there, it's not intuitive what to do next. I've gone to the Utility and selected the flash drive>Bosendorfer sounds, but then don't know how to load the sounds. I don't know how to select loading the sounds to the internal performances.

Mark wrote:

Thanks Michael. I had already unzipped and copied the file onto a flash drive and inserted that in the Montage. But once it's in there, it's not intuitive what to do next. I've gone to the Utility and selected the flash drive>Bosendorfer sounds, but then don't know how to load the sounds. I don't know how to select loading the sounds to the internal performances.

Pages 174-175 in the Reference Manual cover it

Place the drive with the unzipped file in the TO DEVICE port.

Press [UTILITY]
Select "Contents" > select "Load" > there should be box representing your USB drive, touch it to open it
set CONTENT TYPE = "Library File"
Find the "Bosendorfer.X7L" file, touch it.

The LIBRARY file does NOT overwrite what is your Montage's current USER memory. It installs this file directly to the Read Only Memory area of the Flash.