@SimplyShaina994 There is, unfortunately, nothing you can do here, at least not with a Mac. Your codes can't be used a second time, and EA won't give you new ones for a secondhand copy of the game. The installers on the discs are 32-bit apps, as is the game itself, so neither will run in your OS. The only version that would work is the 64-bit version, which is only available in the EA App; it was never released on disc.
It's unfortunate that people sell used copies of Sims 3 without clarifying that they can't be registered. Some players do want disc copies, even if (and perhaps especially if) they own the game in the EA App, to get around having to use the App to launch the game every time. But that's only a viable approach in Windows, which still supports the installer and game in their original 32-bit format.
