Sims 4 on Steam not launching - error message link2ea://launchgame

Hey there.

I bought this game on Steam a few days ago, installed it, made an Origin account, launched it, no issues. It ran fine. The next day I bought some DLC, also on Steam, and wanted to play again. But I can't launch the game anymore. Whenever I try to launch the game I get the same error, no matter whether I try it from Steam or from Origin.

"There is no program associated with this action. Please install a fitting program, or create an association in system settings under "standard programs" if one is already installed."

This happens every single time. I tried uninstalling Origin and reinstalling it again. I tried uninstalling Sims 4 and reinstalling it again. I tried uninstalling Steam and reinstalling it again. Nothing helped, I always get this message when I try to launch the game.

The DLCs have been properly activated in Origin after buying them on Steam, so I don't think they're the culprit.

This is really frustrating and only confirms my view that DRM only hurts the paying customer.