The Exchange Event Provider can connect to either Exchange Web Services (EWS) or Microsoft Graph Api.
Exchange Web Services (EWS) API
Events2HVAC and the Microsoft Exchange event provider require all of the following to function properly:
•Microsoft Exchange Server (2007 SP1, 2010/SP1/SP2, 2013/SP1 and later) or Microsoft Office365
•Exchange Web Services (EWS)
•OAuth Application Credential with read only application permissions on Exchange - Full_access_as_app
Microsoft Graph API
•Microsoft Office365 (O365)
•OAuth Application Credential with read only permissions on Graph API - Places and Calendars
Note: MS Graph API is recommended since the EWS API is no longer being maintained by Microsoft.