You should really be running at least V8 or the just released V9 EMC for Windows by now to support all the latest Office 365 EWS Exchange mailbox Oautho 2 standards required now.
What Windows OS version are you running ?.
However eM Client version 7 and later do support oAuth 2.0 but some peeps haven’t got their eM Client 7 versions to work due to maybe eg: different types of EWS Exchange standards.
See this thread on V7 eM Client and Office 365.
https://forum.emclient.com/t/does-em-client-support-microsoft-oauth2-office-365/73307
I personally have run the latest V8 & V9 for PC and Mac with EWS Exchange Microsoft servers and they work fine with the eM Client automatic email wizard. I only used normal Microsoft IMAP when I had V7 so cannot test with that version.