Hi alphasystem, welcome on these forums and thank you for your purchase!
I do not completely understand your question. Is this a typical Divi theme (page builder) thing where you can enter a URL? Is that a page element and what does it create then on the front end? A link?
If the element has advanced options, look for a way to append a “class” to the link. Then set that class to “fancybox”, “fancybox-inline” or fancybox-iframe” or other (depending on whatever the URL points to).
Else, try a simple “text” element…
Or maybe I misunderstood. Then please share a link to the page where you are trying to get it to work 🙂