Hi Katie,
Looked into your site, there are two types of JS errors on the page.
One is about “You have included the Google Maps API multiple times on this page. This may cause unexpected errors.”. This error is coming because you have also included Google MAP API via WP Google Maps plugins. But this JS error not breaking any things on pages.
Second JS error is coming from “Popups – WordPress Popup” plugin, and this error breaks things on Add Listing page. To fix this i have excluded Add Listing page from Popups > All Popups > Subscribe Edit > Popup Display Rules. (see last third condition).
Now seems add listing page works fine. Please check i have added 2 test listings.
If you still find any problem, then let us provide FTP details.
Let us know.
Thanks,
Kiran