Re: Sims 4 DLC bought on EA/Origin won't load in Steam
@Petalcat When you install Sims 4 through Steam, you need to download your EA-owned packs into the Steam install. This is simple to do when you only have the Steam version of Sims 4 installed, but the EA App may not allow you to do this, saying the packs are already installed, if you have both the Steam and EA App versions on your computer. Point is, uninstall the EA App version of Sims 4 and reinstall the Steam version, then download your packs (but not the base game) from the EA App.
Or you could get your money back from Steam and buy the kit from the EA App. That's the simpler choice, all else being equal.