Unable to add account. Please try using the Outlook Web App on Mac OS

When trying to add account on Microsoft Outlook web app on MacOS, I get greeted with this message (title). With username name.surname@encomdoo.onmicrosoft.com i can log in on Web app and in Windows desktop app, but it won't let me log in on MacOS desktop app with the SAME account. (I wrote this becaus on support they said that account doesn't have a mailbox, which is incorrect because I'm using the same account to log in on Windows)

Anyone else had this issue and how to resolve it?

Thanks.

[Re-Titled by Moderator]