The trick here is that you do not set up your registration page in Zoom. You set up your Webinar program in Marketo to link with the ID of the specific webinar. You have to make sure that, when a person registers, they are updated to Program Status Registered in Marketo. That is the trigger for the lead to be synced to your Zoom webinar as registrant and a personalized webinar url to be returned from Zoom to Marketo.
Although the sync of the person should also trigger your confirmation email in Zoom, I would actually suggest to move that process step to Marketo as well. As Zoom will feed back the personal webinar url for the person who registered, you can run your entire communication through Marketo, controlling your branding and email responses much better than from Zoom. I would run a quick test to assess how long it takes for the webinar url to be returned, so you can make sure you send the confirmation email once you are sure you have that back in Marketo.
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