Outlook in Office 365 kept hanging and wouldn’t add an email account on a fresh install of Office 365. It took me almost an hour of troubleshooting. I went through the normal steps. That included running a repair, trying a new profile, removing office credentials in windows and recreating the ost file.
The other thing I tried to focus on was Office activation. It said it was activated but when you opened Word the sign in button on the top never changed. It would ask you to login and when you did the Sign in remained.
This lead me to believe that it had something to do with activation even though it said it didn’t. My searching came up with a suggestion to edit the registry. After looking at the entry I didn’t think it would work. Sadly, I was wrong.
A post on Microsoft’s answers had the solution. At the time I was not sure what ADALatopWAMOveride was but it worked.
HKEY_CURRENT_USER \ Software \ Microsoft \ Office \ 16.0 \ Common \ Identity Name = DisableADALatopWAMOverride Type = DWORD Value = 1
Just add the above key as a DWORD and then go back to Word and sign in. Once you are signed in then go to Outlook and it will pick up the correct credentials.
ADAL or WAM authentication is Azure Active Directory Authentication Library and Web Account Manager. ADAL is needed for MFA. I did confirm MFA was not turned on for this user’s account. We also have a hybrid AD environment which does appear to cause some quirks.
After reading some more information about this issue it sure does seem to have something to do with your hybrid AD in some form. I’m sure we may experience some issues with that key in the future but it at least is working today.