Sorry to hear you are having a hard time setting up Hustle. After looking at your site I am wondering if Hustle is encountering a conflict with your theme or another plugin. You can test for a theme conflict by switching to a different theme and checking to see if the pop-up appears. To test for a plugin conflict, turn-off the other plugins on your site and check to see that your active pop-up is working. If it is, reactivate one plugin at a time until you find the conflict.
I see that you have a pop-up being triggered with the Apply Now button that is working. This may be causing the conflict. Also the Contact Forms 7 is sending errors. Let me know how your test goes!