You can open the "PalWorldSettings.ini" file, search for "Steam" or "AllowConnectPlatform," and simply replace "Steam" with "Xbox." Please make sure you are only editing the word "Steam" to "Xbox," then hit save.

I’ve found a guide in Citadel Servers’ knowledge base that I think will help you solve your problem. You can check their guide here:

https://citadelservers.com/client/knowledgebase/599/How-to-change-your-Palworld-Server-from-Steam-to-an-Xbox-one.html

Many other guides in their knowledge base may be helpful to you in the future.