We have purchased 15 licenses of Dorico 3.5 and on the downloads page along with the installer is an 8.6GB download containing ‘additional content’ called "Dorico Pro 3.5 · Sounds Installer (Content) "
On extracting the download there is no install program just a bunch of files but I dont know what to do with them!
Do they need to be imported in to the Dorico software or do they just need to be saved somewhere so the users of the software can browse to them and open them up as and when needed?
It could be that the location where you have unzipped the downloaded zip archive has exceeded the maximum allowed path length on Windows, resulting in some files being missing from the unzipped archive. More information here.