Anyone know how to track booked Meetings using Google Tag Manager?

Thank you so much for sharing! I tried reading through these as well, but my thought was maybe I wouldn’t be able to track the bookings through GTM using these steps because mine happen in an external page hosted via Hubspot and the calendar is not just embedded on my page. We have a “Book a demo” CTA on our site that’s just an svg button, if a user clics on it, then a new window opens that takes them directly to the HS Meetings Link.
The most I could do in this case was create something that listens for the clic on that button, but I know a lot of people might drop off and not actually complete the booking which is the second layer of data that we’d love to be able to track using our pixels/insight tags to count the actual conversions (Facebook/LinkedIn Ads). Any thoughts on how one might be able to do this? Do I need to change anything on the actual page and that CTA button first?