Hi @Mathias Petersson ，
Outlook app will not setup the e-mail, tried these types of account:
Could you configure other account in Outlook client normally except this o365 account? And has this issue occurred only recently? If so, have you performed any specific operations before it?
Did it display any error when you configure it? If so, please provide us with the detailed error information.
Have you logged into your web mail on your pc or your mobile? If you haven't tried to log in your web mail on pc, it's suggested to first try it. If you also couldn't log into it normally, the issue may be related to your pc, it's suggested to first check your internet and switch to other internet to check if the issue has any difference.
If it work normally on your web mail, the issue may be related to your outlook itself, so what's version of your outlook client(file>office account>about outlook), please first ensure that you have updated to the latest version of outlook.
As I know, any anti-virus programs may also affect the connectivity of Outlook and server, it's suggested to close other antivirus programs temporarily to check if the issue still exists.
Also, if the issue occurred only recently, in order to avoid the interference of corrupted outlook profile, it's suggested to create a new outlook profile and readd your account to check.(control panel>mail>show profiles>add>readd your account)
If the issue still exists, for Microsoft 365 account, we actually supply SaRA tool that works by running tests to figure out what's wrong and offers the best solution for the identified problem, please kindly download and check if it could fix your issue.
Hope that would be helpful to you, if your issue has any update, please feel free to post back.
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