I did it last week and always got an error trying to create a new microsoft account during the migration process, even in different browsers and after disabling adblockers. Then I just manually created a microsoft account on the microsoft website and in the minecraft migration process chose to use an existing account instead of creating one. That worked for some reason.
PSA: If you still have a Mojang account for Minecraft: Java Edition, you have less than a week left to migrate to a Microsoft account to avoid profile deletion angielski
Thought I’d share this in case there are people who are unaware or have been pending off the migration process....