First thing, you shouldn't download plug-ins from GitHub unless you are really confident of using them or looking forward for some additional development that you expect or asked for, download plug-ins from Moodle plug-ins directory where stable releases are uploaded.
So for this plug-in, you should be looking into page
https://moodle.org/plugins/local_o365
alternatively you can as well look into https://moodle.org/plugins/local_office365
Both plug-ins are updated for latest Moodle.
Now for your issue, have you disabled blocks/activities from your moodle?