g683mj7omfm7 Please uninstall Sims 3 as described here:
https://bluebellflora.com/how-to-do-a-clean-uninstall-and-reinstall-on-a-mac/
Since you're willing, please update your OS to Catalina, Big Sur, Monterey, or Ventura whichever you prefer. (Ventura is the newest OS that supports your model Mac.) Here are links to the installers for all newer versions, plus brief instructions:
https://support.apple.com/en-us/102662
Once you've installed the OS of your choice, install the EA App:
https://www.ea.com/ea-app#downloads
This will automatically remove Origin. Login to the App with your EA account details and download Sims 3 from there. If you can't, let me know what happens when you try.