Girlxpop That's an old thread, and EA has reorganized its support portal a couple times since then. Now you'd start here:
https://help.ea.com/en/customer-care/
Fill out the form and look for a live chat option. If you don't see one, choose a slightly different category of issue. Once you're talking to a real person, explain that you need the 64-bit "entitlement" for your base game, and make sure you get the entitlements for any packs you own too.
This is the master thread for missing 64-bit entitlements, which usually throws an error that you didn't mention. That's why I didn't merge, but if you are getting that error, let me know.
Redeemed Sims 3 codes but wont download as says only available on windows? | EA Forums - 11143008