Situation: When attempting to run Outlook 2011 on a Mac, it promotes for a domain user password as shown below, but can't login.
Troubleshooting: 1. It could be default keychain issue. Please refer to this page: You enter an invalid password when login Microsoft domain in a Mac
2. Make sure you enter correct password.
3. The keychain may be corrupted and need to rebuild. Please refer to these posts: How to reset keychain in Mac, How to repair Mac keychain or How use Keychain First Aid utility to sync password
4. Delete user profile from the Outlook and reset it.