Transferring CC from one computer to another

I think the files for Mac are a little different from PC, so they're not entirely cross-compatible, especially since the files within the game could be named/numbered differently across platforms but also EA stopped supporting Mac a while ago so the files are older and there's a stronger chance something could be broken in general. (Edit: Okay, found some info, they stopped supporting Mac OS Lion 10.7 and while there are some potential bugs with Mac OS X 10.1 (Yosemite) I guess they're still supporting it? IDK if that's relevant then so maybe disregard.) Also, make sure you're using the PC version of Sims4Studio now and that it's as up-to-date as your version of the game.

I'd recommend going online and downloading the mods again but also check when they were last updated and if the creator is maintaining them. If the last known online version is still pretty old, maybe test them out independent of the other CC to make sure they still work. If the rest of your CC isn't an overwhelming number, like over 10,000 CC files, I'd consider redownloading most if not all of it and then running batch fixes related to packs/patches. You can also run batch fixes first but I have a strong suspicion that won't solve the issue on its own. I hope that helps!