Minecraft Multiplayer with Microsoft Account?

Is it even possible to play multiplayer with a Microsoft account? You can't do that with a friend and neither of us know how to change that. Does anyone have a solution for that?

Yes it is possible but you probably need another one to play online. XBox Account! You create it via the Xbox app or website / Xbox which gives the e-mail to which you also entered your Microsoft account! That the two can automatically link.

Or what are you actually playing at?

Both on PC

Yes, it is.
Your friend needs to set the option You can play with players outside of Xbox Live to Allow and click Submit under the following link:

https://account.xbox.com/de-de/settings?activetab=main:privilegetab

Do you already have an Xbox account?