You need to create a PHP Class to authorize client-app and get all calendar events from all users in Office 365 organisation. This will include building the backend part of an experience like "Sign-up my Organization" to accomplish the initial one-time consent. the access token are then saved to the DB for future access to the API.
Hours to be determined
Less than 1 month< 1 monthProject LengthDuration
I am looking for a mix of experience and value