Re: Cannot download sims 4 DLCs on EA desktop with Steam base game

@llluvvc  Please do a clean uninstall of Sims 4 with Revo Uninstaller (the free version is fine).  Before uninstalling, go into Documents > Electronic Arts and rename the Sims 4 folder to something that doesn't include "Sims 4."  This will prevent Revo from flagging it for deletion.  Uninstall the EA App with Revo as well.

Reinstall the game through Steam, plus any DLC you own there.  Reinstall the EA App, then try to download your owned packs there.  If it doesn't work, please post a screenshot of the error you see, or whatever happens instead of a successful download.