Tracking which CTA started the conversion path

Thank you so much @crispyGTM. I have a couple of questions though:
1) Which CTAs ID will be this report tracking? Should I add it one by one as custom CSS or is one that HubSpot delivered by default ? Because I got the same result (No value).
2) How will this CTAs be connected to the forms where they are redirecting (and afterwards converting)?
Thanks again.