I think the admin might have enabled some compatibility features for you, I get:

    ~ $ offlineimap
    OfflineIMAP 7.3.2
      Licensed under the GNU GPL v2 or any later version (with an OpenSSL exception)
    imaplib2 v2.101 (bundled), Python v2.7.18, OpenSSL 1.1.1g  21 Apr 2020
    Account sync work:
     *** Processing account work
     Establishing connection to outlook.office365.com:993 (work-remote)
    Enter password for user '<user>@massive.se':
     PLAIN authentication failed: AUTHENTICATE failed.
     LOGIN authentication failed: LOGIN failed.
     ERROR: All authentication types failed:
     PLAIN: AUTHENTICATE failed.
     LOGIN: LOGIN failed.
     *** Finished account 'work' in 0:11
    ERROR: Exceptions occurred during the run!
    ERROR: All authentication types failed:
     PLAIN: AUTHENTICATE failed.
     LOGIN: LOGIN failed.
    
    Traceback:
      File "/usr/lib/python2.7/site-packages/offlineimap/accounts.py", line 293, in syncrunner
        self.__sync()
      File "/usr/lib/python2.7/site-packages/offlineimap/accounts.py", line 369, in __sync
        remoterepos.getfolders()
      File "/usr/lib/python2.7/site-packages/offlineimap/repository/IMAP.py", line 452, in getfolders
        imapobj = self.imapserver.acquireconnection()
      File "/usr/lib/python2.7/site-packages/offlineimap/imapserver.py", line 586, in acquireconnection
        self.__authn_helper(imapobj)
      File "/usr/lib/python2.7/site-packages/offlineimap/imapserver.py", line 459, in __authn_helper
        "failed:\n\t%s"% msg, OfflineImapError.ERROR.REPO)