If you ever tried to join Azure AD with your Windows 10 client while you were logged on with the Builtin Administrator account, you have probably noticed it didn’t do anything at all. Clicking on “Join Azure AD” didn’t seem to do a thing.
That’s because Microsoft disabled the usage of that functionality while logged on as the built-in Administrator. You can verify this is the issue by looking into your Application log with Eventviewer:
Simply log on with another account (Microsoft or local) and retry and you’ll see it works :)
Some reference information:
Log Name: Application
Date: 1/13/2016 3:38:56 PM
Event ID: 5973
Task Category: (5973)
Activation of app Microsoft.Windows.CloudExperienceHost_cw5n1h2txyewy:App.AppXe35aa078nkgkdbkbrk5tjm2xds5rwz5q.wwa failed with error: This app can’t be activated by the Built-in Administrator. See the Microsoft-Windows-TWinUI/Operational log for additional information.