https://support.zoom.us/hc/en-us/articles/207927346-Using-the-Infusionsoft-integration#:~:text=The%20Infusionsoft%20integration%20allows%20for,and%20automate%20follow%2Dup%20messages

Notes:

1) HTTP Post MUST still have the following fields, even if you don’t think they’re needed:

first_name = Contact.FirstName
last_name = Contact.LastName
email = Contact.Email
questions = Note: This field stays blank.
custom_questions = Note: This field stays blank.
webinarId = Your webinar number

If you’re including a join link and sending links out of Infusionsoft, you also need the field below. We don’t usually do that.
joinLinkField = Infusionsoft custom fields for the contact record
Example, joinLinkField = _WebinarJoinLink2

2) You must add the Infusionsoft Integration from the Zoom App Marketplace, NOT the Keap Integration. They do different things.
3) This only works to register folks for Zoom Webinars, not Zoom Meetings.