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)