Hi there,
I found the setting which seems crucial regarding the shown error. In retrospect, it’s logical. But the error message is not.
You need to set “You can see and upload community creations” in privacy settings to “everyone”. I assume it’s related to the mods and the associated multiplayer settings.
Please, specify the error message asap. “User Privilege Error!” is far from meaningful. Had a 40 minutes talk with Microsoft Support, they had no idead how to help me. Checked half my system with support, didn’t work out the problem. I was about to give up the game still I started to test every privacy setting after “Nexus26”'s hint (thanks!).