In integration Marketo with Zoom Webinar, how CORS works

I would like to integrate Marketo with Zoom webinar.
Please confirm the security measures when using their APIs.

Is it correct that the information for authentication (Client ID and Secret Key) created
through Marketo integration can only be used from the application server
(i.e. Marketo server)?
According to the explanation on Zoom’s website regarding OAuth2 authentication
https://developers.zoom.us/docs/integrations/oauth/
when using Zoom APIs, it seems that API endpoints must be called from the server side,
as calling them from the client side will throw CORS errors. In the case of integration
from Marketo to Zoom Webinar, the “application server” mentioned in the explanation would
refer to the Marketo server. Therefore, it can be inferred that the authentication
information (Client ID and Secret Key) created through Marketo integration can only
be used from the application server (i.e. Marketo server). Is my understanding correct?

Regard.