How to fix "Multiplayer is disabled. Please check your Microsoft account settings." in...

Hey, so I bought a Minecraft account for my child a few hours ago and when he starts running the game on his pc, he can't click on the Multiplayer button. It says "Multiplayer is disabled. Please check your Microsoft account settings." I've already tried everything and still can't figure it out. Thank you for your help and have a nice day.

:)