Hi
@Lexi290So from what you've stated so far, I think it's safe to assume that you are running MacOS Catalina, which has removed support for 32bit applications & games and has deprecated OpenGL in favor of Metal.
Due to this, The Sims 3 in its current form would not work on the latest version of MacOS requiring essentially a complete port of the game over to the newer version of MacOS.
Luck for you that new port recently released, about two weeks ago to be precise and hence why you are seeing two copies of the game in your library. One that is playable and one that is not.
What I would suggest is that you have a quick read through this article:
https://answers.ea.com/t5/Technical-Issues-Mac/An-announcement-for-The-Sims-3-players-on-Mac/td-p/8271641Paying special attention to this excerpt:
"I have The Sims 3 DLC and/or content from The Sims 3 Store. Do I need to re-purchase them if I use the new version?
No, all of your existing packs, Worlds and purchases from The Sims 3 Store stay with you. To install your Packs, you will need to download them once you have installed the new version of The Sims 3. You can do this by selecting The Sims 3 (64-bit & Metal) from My Game Library in Origin and selecting each Pack type and clicking the Download button. For content purchased from The Sims 3 Store, login at TheSims3.com and go to Store > My Store Account > Purchase History and you will see your purchases ready for download."
Your Origin account details should log you into the Sims 3 site. If this does not work and you still do not gain access to your expansions. Then I'd suggest you contact support and request that they add your expansions from their side to the 64bit/Metal port of Sims 3.
Hope this information helps
Take Care