Link Minecraft account?

I bought Minecraft and it immediately synced with my Xbox account. I have only one problem: I have to log in to a Mojang account for a project (so I didn't try to do one) and the last step is to buy the game but I've already bought it. Can someone tell me how to connect my Xbox account to a Mojang account? Or how can I solve the problem?

As far as I know, Mojang accounts are only relevant for the Java edition. You have to buy this version of the game separately. You can only connect MinecraftPE to your XBox account and play like this.