If Office apps for Mac keeps asking for your password but does not accept your password when you enter it; follow the steps below:
1) First check to see if you can log into your account at Portal.office.com (If you are not able to login to portal.office.com, it could be that your password is incorrect. If so, please contact the support desk.)
2) If you are able to login to portal.office.com next ensure all office apps are closed, then open up Keychain and log in
3) Once logged in search for adal, and remove the following:
3) Then try to load up Outlook and sign in.
If the issue continues after trying the above, please contact the Support desk.