I own the Game Pass Ultimate from XBOX and downloaded Kingdom Come Deliverance for free. Now I would like to buy the DLC From the Ashes. Does this work even though I only have the game through the Game Pass?
It works, but keep in mind that you don't own the game.
Sure, but as long as I pay for the Game Pass I can play the DLC
Yep
Okay thanks, have you done it yourself before?
No, but you can be sure that it is. You even get a discount on DLCs from GamePass games.
https://beta.support.xbox.com/help/subscriptions-billing/manage-subscriptions/xbox-game-pass-faq
