Before Origin was a thing, I had a Sims3 account. I am trying to access it so that I can get my Sims Store purchases, but every time I try, it sends me to Origin.
@mnoble22 Store and Origin accounts are now tied together—information from one flows to the other. I'm not sure how this works for accounts that predated Origin, but I'd expect that either the information was already shared and you do in fact have an Origin account, or you just need to sign into Origin to import the info.
Specifically for store purchases, though, you shouldn't need to use Origin at all. Store content is still downloaded directly from purchase history; it can be done on a computer that doesn't have Origin installed at all. Are you trying to reset your password? If that's not the source of the redirects, try clearing your browser cache, or using a different browser entirely. I suppose it's also possible that the store recognizes your lack of an Origin account and is trying to force you to officially create one by logging in, but that's pure speculation. Still, you could try signing into Origin (either the app or the website) to see if it interrupts whatever loop you're currently caught in.
One thing that you do need Origin for is buying more SimPoints; the store no longer handles these transactions. But you can do so from Origin's website, not just the app.
If you're having trouble accessing your account for whatever reason, you'll need to contact EA customer support. As long as you still have access to the original email address associated with your store account, a support rep will be able to reset everything and restore access.