Do you have 2FA enabled for the Microsoft account? What server names, ports and encryption are you specifying for the incoming and outgoing servers? Have you read discussions about it on Apple's web site? https://discussions.apple.com/thread/255662904?sortBy=rank
Also, check this article: https://www.techsolutions.support.com/how-to/how-to-set-up-outlookcom-email-on-mac-mail-13007
These web sites are not Microsoft sites, but they appear to contain accurate information and no unwanted apps. They may use cookies, however.