How do you make a Mojang account if you already bought Minecraft?

I bought Minecraft on the Microsoft store. I tried to make a Mojang account but it tells me to buy Minecraft when I already did.

Guest 07.04.2018

Minecraft Mojang (Java) and Minecraft Windows is a different version of Minecraft

Minecraft Windows, XBox, Phone is in the same server, but Minecraft Mojang have it own server.

Guest 13.04.2018