Re: Can I buy DLC from EA App for game owned on Steam?

@theparda  Store worlds are installed through the Sims 3 Store regardless of what type of install you have.  Please see the first post of this thread for more information:

https://answers.ea.com/t5/Store-Issues/Sims-3-Store-world-can-t-register-install/td-p/12619800

To buy these worlds, you'll need to install the EA App or else use the EA store website, but then you can register the worlds and download them into your Steam install.  There's no need to install Sims 3 through the EA App.  Just make sure that your Steam copy of Sims 3 is registered with EA, which you should be able to confirm just by signing into the Store and seeing your content under My Page:

If you've never registered your game, you can do so now, using the CD Keys Steam provides on the Store site or within the EA App.  Just make sure you're signing into the EA account, by email address and password, you want to own the game and make future purchases.

I have a Steam install myself and have no trouble installing Store worlds.  I bought them all in the Origin days, through Origin itself, without installing the game.