If you have created, or attempted to create, a symlink to store your Electronic Arts/The Sims 4 folder on an external drive head over to this thread instead - https://answers.ea.com/t5/Mac/-Creating-a-symlink-in-macOS-to-store-the-Sims-4-folder-on-an/m-p/12329439
Go to System Preferences/Settings > Privacy & Security > Files & Folders and make sure the game has access to the Documents folder. If your game is installed on an external drive it also needs access to removable volumes. Or System Preferences/Settings > Privacy & Security > Full Disk Access and give the game full access.
If you're really stuck, set up a new user account on your Mac and make sure you allow all accesses when prompted by the OS.
