Hi, I'm following this KB:

One caveat is that I'm putting the form in a popup. So I need advice on step 9: the NEXTURL.
What would you do? NEXTURL to my thank you page and open on top of the Original Page? Can I code NEXTURL to open in a new tab? Can I code something to say Thank You within the confines of the popup box, then the user closes?
I've seen some other users chat about this from a few years back so I hope there's good intel out there!
Thank you!