zoom registration page with get-parameter

It won't be prefilled in the forms based on the url parameter. You can use tracking sources to create a separate link for each source. If you want more granular analytics you could create your own registration forms using APIs that does prefill based on url parameter. If you are not a developer there is a Zoom app, Salepager, that lets you create a registration form to track the source of your sign ups based on link parameters.