Did they try installing the mods from Nexus Mods or the Steam workshop first?
If they have a problem with Steam not copying the mods to the game folder, they can do so manually. A handful of people have reported this issue with the Definitive Edition of the game.
Search the '..\Steam\SteamApps\workshop\content\435150' folder for *.pak files, sort by date modified and copy the recent ones to the '..\Documents\Larian Studios\Divinity Original Sin 2 Definitive Edition\Mods' folder manually.
You can also transfer the files from your own computer, by email, or zip them and upload to Dropbox or Google drive (or a site like wetransfer.com).
If you've done that but still have issues, try using a file comparison program to make sure you have the save versions of mods.
If you each use a program like DVDSig or ExactFile to scan your mods folder, and swap the resulting files to verify, it would identify any differences between the folders (missing, outdated or corrupt mods). Unsubscribing and re-subscribing to mods where there are differences should presumably make sure everything is up to date, or redownloading from Nexus Mods.DVDSig
is tiny (alternate download
), portable and doesn't require an install, while ExactFile
has more features.
Alternately, especially with only a few mods, you could use a program such as Hash
to create a list of checksum values to compare manually (slightly more work comparing, but no file swapping).
If the mods are all identically, and all extras (like Norbyte's script extender) that need to be installed are, but you still get a transfer when trying to play, try each creating a new profile and testing in a new game without mods. If that works, enable half the mods and try again. If you get the transfer disable half of the ones you enabled and re-test, otherwise enable half the remaining mods. With a little trial and error you should be able to identify which mod(s) are causing the problem, or if any mod will.