Not able to edit the form

We have used this plugin to create a user registration form when the user purchases a product from our e-commerce store- https://infinitychannelswimming.com/product/open-water-swim-full-weekend/.
Everything was working fine. And now when I opened it to add another form, the backend stopped working.
The form fields and settings option shows nothing- just text and when I click on the dropdown icon to add it does not work.
PS-I recently updated the WordPress version and installed the SSL certificate to the website.

The page I need help with: [log in to see the link]