OAuth2.0 Authentication and Communication to Exchange in Zoom Rooms Calendar Integration

I have a question about OAuth 2.0 authentication and communication to Exchange for Zoom Rooms calendar integration.
If you know the answer to this question, please respond.

■Question
In the past, when we used EWS authentication (legacy authentication) for Zoom Rooms calendar integration, communication from Zoom to Exchange occurred irregularly on the M365 side.
However, after changing from EWS authentication to OAuth2.0 authentication, communication to Exchange has not been confirmed.

We were aware that the communication to Exchange was polled from Zoom (AWS), but with OAuth2.0 authentication, is it OK without polling?
(Is polling no longer required?).

I apologize for not understanding, but could you please tell us what polling is for and what is the reason for the communication that occurs in the first place?