@yanmaisee You can only register a code once, so the error message you received is entirely expected. The code is tied to your account, and once purchased, TS4 should show up in your Origin library no matter which computer you use to login, without your having to reenter the code. You wouldn't need to buy a separate standalone version of TS4 for mac unless you wanted to add it to a separate account. However, Origin Access is only offered for Windows, so any game you have through Access will not be available on a mac.
I'm not clear on which accounts you're using when you look for TS4, but just to reiterate: Your original account—the one that you used to purchase the PC version of TS4—owns the rights to play the game in both Windows and mac OS. You should be able to use this account to download the game onto your daughter's imac without needing any more codes. But whichever account has Access will not be able to use Access, or any games owned through it, on a mac. I believe that in this case, the Access-related content might not even show up in the Origin library.
If you want to sort out any billing issues, it would be best to contact EA customer support. No one here can see your account details, much less revise them.
