This error can appear for Microsoft Store and Steam users when trying to log into Xbox. There are two known causes:
- The Xbox service is currently unavailable
- You appear to be in a region where the service is not available
If you purchased the game using a VPN or are playing using a VPN, you will not be able to access Xbox and any of the associated multiplayer features if you are playing in a country/region where Xbox products and services are not supported.
Xbox Supported Countries & Regions | Xbox
Additional details can be found in this article.