At your forum site I don’t see an option to login with a Microsoft account, you say there is a plugin already enabled for that so it should be possible?
For the hive forum it looks like that can only be accessed with a Microsoft account for login, which contains xbox account information.
I may be able to help to develop this feature for your site, but for writing code I don’t have background in that is not my field. Jay or someone else here hopefully can do that.
For this marketplace looks like you are supposed to post if you have a specific budget for a project.