@simsashes Try contacting EA customer support and asking for help. Apparently for some users at least, something needs to be reset on the EA side. This issue isn't exactly the same as yours, but it sounds similar enough, and a support rep did something, I'm not sure what, to fix it:
https://answers.ea.com/t5/Technical-Issues-PC/Sims-3-launcher-won-t-let-me-re-download-store-bought-content/m-p/13600067#M264958
I would strongly recommend using live chat rather than email. If you don't see the option, try this link:
https://help.ea.com/en/help-contact-us/?product=the-sims-3&topic=missing-game&category=manage-my-account&subcategory=find-missing-game
Make sure you're signed into an EA site (this one is fine) before clicking the link and that the location in the lower-right corner of the browser window is set to U.S. or U.K.
If you don't get anywhere with support, let me know, and I'll ask around to see if there's anything else you should do or request.