Zoom for Salesforce Lightning Integration - Can you sync to existing webinars

I have just installed the new Zoom for Salesforce Lightning integration app into my Salesforce instance. Before this install I had created many webinars into the future the people are already signed up for. I don't see any mention in the documentation on how to sync these pre-existing webinars to Salesforce. There is no 'button' in the Zoom portal page for each webinar to 'sync to Salesforce'. And in Salesforce, I can only create new webinars which will automatically sync to the Zoom portal, but I see no place in Salesforce to grab existing webinars from Zoom. Is there any way to accomplish this?