John on Progressive Foundry MAC Installer Issue

Can you access the contents of the USB drive?
If so, you should be able to install the sounds manually as per the instructions in this FAQ:
https://www.toontrack.com/faq/im-getting-an-error-could-not-copy-soundb-obw-file-when-installing/
It describes doing it from DVDs but you should be able to do it from the USB drive as well.