Sims 3 always stuck on second loading screen Macbook pro

camagatha  I think it's worth reinstalling macOS.  This doesn't need to delete your data—there's an option to preserve everything while simply replacing the OS files.  Here's how:

https://support.apple.com/en-us/102655

Please try again to play in the new account.  Clear the EA App's cache:

https://help.ea.com/en-us/help/faq/clear-cache-to-fix-problems-with-your-games/

and repair the game again, then play online, and if that doesn't work, offline.