So, I bought this game for a few people hoping to play with them (all on PC), but one of the people is unable to login due to the error: "The account you're attempting to sign in with is not provisioned for this environment. Your app may not be configured correctly." 

Has anyone else gotten this error, and is there a fix for it? 

This person has tried reinstalling everything multiple times, restarting/stopping processes, using command lines in cmd prompt and pretty much trying everything I could google about login issues for hours, nothing has worked.  I think they are also unable to install the xbox live game app for some reason, it also results in an error.

BUMP
This just started happening to me after the new update today 

Hello!

I'm sorry you both have run into the Account Provision error. Our team has resolved this on PC, and everything should be working correctly now. 

Please don't hesitate to submit a support request if you run into this again or any other additional issues. 

Obsidian Support

Cheers!