Physical copy of game, can't download onto computer

ThatKiddEm95​  If you already registered the code in the EA App, or Origin, or on the old Sims 3 site, you won't be able to use it again.  That's normal.  But it should also appear in the EA App game library for whichever account used that code at the time.  If it's not appearing in this account's library, try to login to the App with any other email address you currently have access to and see whether you can find the game there.  You can click "Forgot your password?" to get a password-recovery email.