Measure registrations using Gravity Forms

Hi All - Can anyone confirm the form on this site is a gravity form?

I looked at the source and saw it was.

Secondly, can I measure the number of registrations using Facebook conversion events? We will be advertising this event and want to measure registrations.

Lastly, If Facebook ads can’t - should I use GA?

I unfortunately don’t have access to this site but have been told its not possible to measure the number of registrations?

In GTM - is creating a trigger ( form submission) enougH?

Please help,