Recently, Outlook Mac users having trouble signing in after password changes or adding new accounts. The login process goes into a loop since Outlook promptly asks for the password again, even though the user has entered their credentials correctly. After a few tries, users face this error: “Check your credentials and try again.” As there is no specific error code apart from the general warning above, they cannot find a clue about the cause of the problem.
Unfortunately, some known troubleshooting doesn’t help in solving this problem such as Clearing the office credentials on Key Chain Access, reinstalling the office apps, and Re-creating the Outlook Mac profile or the Mac user profile.
SOLUTION: Microsoft development team announced that this issue is a bug and they will fix it in the backend as soon as possible. This issue affects those who use Office apps in Turkish or some specific languages.
WORKAROUND: If you change the MacOS and Outlook language to English (or other than the language you use), your problem will be solved. Many users fixed their problems with this method. So, you can overcome the problem without waiting for the Microsoft developer team.
To implement this, you can browse the Microsoft document in the link or follow the steps below.
On macOS, open System Preferences>>Language and Region menu, under Preferred languages if English is not added, add English by using the + button. Then you can drag and place English to the top as the primary language. After this process, MacOS will be restarted. Once it is restarted you will see that Mac and Outlook language changed to English.
This workaround works for many users. I hope this method will solve your problem as well.