RebeccaRob08 You've installed the game into Documents, which is a problem for various reasons. and should be addressed first So please copy the saves and Tray folders here, as well as Screenshots if you care about those, to another location on your computer (not in Documents, but the desktop is fine). Then uninstall the game through the EA App, and clear the App's cache:
https://help.ea.com/en-us/help/faq/clear-cache-to-fix-problems-with-your-games/
Restart your computer and install Sims 4 elsewhere. The default C:\Program Files\EA Games is fine, as is a custom location as long as it's NOT in Documents or Desktop.
Once you've done that, start the game again and confirm that the user folder is still in the same location. Open that exact location and look for a Mods folder. If you're not sure whether you're in the right folder, or you don't see a Mods folder, you can open the location manually. Click This PC in the left panel of a File Explorer window, double-click the C drive, and open Users > your username > Documents etc. from there.