Melcakiroglu The game and launcher have trouble with passwords that have special characters like & or !, and possibly with accents or letters that don't appear in the Roman alphabet. So if your password has any of these, change it to something with only Roman letters and maybe numbers.
If that's not the issue, open Keychain Access, inside Applications > Utilities, search for sims3 , and delete any entries you see. Then try again to login at the Main Menu.
If that doesn't work, delete the Keychain Access data again. Additionally, open Documents > Electronic Arts > The Sims 3 > Downloads and delete the file labeled [your email].bin. Finally, clear the EA App's cache.
https://help.ea.com/en-us/help/faq/clear-cache-to-fix-problems-with-your-games/
In case it's not clear, you don't need to login in order to play or to install your expansion and stuff packs, and you wouldn't need to login to install your Store content if not for the issue with the launcher crashing in macOS. It sounds like you might only be talking about Store stuff, but just in case you thought the login was required in general, it is not and has never been necessary.