I'm struggling to get Popup Pro to work on my site with a MailChimp signup form. I read on your support pages that I should be able to just copy and paste a MailChimp Embedded form into the text editor, and it should work, but it doesn't. I've tried using the MailChimp icon in the Wordpress editor toolbar (from your MailChimp sync plugin) but that doesn't work either.
Rather than explaining everything here, probably not very well, I've set up a staging site and a test list on MailChimp so you can jump in and take a look. I've disabled all other plugins etc. and I've tried switching to the Twenty Fifteen theme, and I can't even get the popup preview to display for my Wordpress form.
I'll enable access to my mbpvest.com (staging site) for you to take a look.