Sounds like you authorized using the wrong account. Also, you definitely need to upgrade to v1.17.3 and install the latest build of the OAuth2 plugin. Once you do this Delete the current token, visit osTicket in an incognito/private window, login as an admin, go to the email authentication config popup, submit the email config popup, when it brings you to MS authenticate as the email you are configuring in osTicket, consent if it asks, and then you should be good. Otherwise you'd need to make sure IMAP is enabled for the email address in Exchange.
If you do all of that and still run into issues it's likely an issue with the app registration or OAuth2 config. If this is the case you'll need to follow the documentation in thorough detail: