How to switch from a local user to Azure AD user?

Hi everyone. Since this is Windows 11, I did not try to revive this thread since it's on Windows 10.  I did expect the procedure to add the account the be same, but it does not work.

Once I add the user via 'Accounts > Access Work' and select 'join Azure AD', I get him listed as
'his.email.address (work or school account)' but contrary to the laptop our actual admin (who I'm currently filling in for) recently set up, I don't get him listed under 'Accounts > other users' as
'AzureAD\JohnDoe', not even after having rebooted. And not even after clicking on 'Add account' and using his E-Mail address cause then I'm told that I can't use this option to add a work or school account.

I CAN add him with his Email under 'Accounts > Add work or school account' but once this is done he's listed there twice:

Connected by his.email.address (connectec by our.company-MDM)
his.email.address (work or school account)

and I STILL can not log in with the AzureAD user.

So, where do I add the user so I can switch between local admin user and Azure AD user on the login screen? Thx!