What is CRM-based Conversions API?
The Conversions API is a server-to-server way to send events to Meta. It does not depend on the browser, cookies or ad blockers, and it can carry data the browser never sees.
A CRM-based setup uses that channel for what happens after the form: the lead was qualified, the visit took place, the deal was won or lost. Those outcomes are what you want more of, and ad platforms cannot see them on their own.