Empty category selection field

When you add a new ad from the search engine, category selection does not work. It happens on my website and in your demo after registration:
https://radiustheme.com/demo/wordpress/classified/listing-form/

Before we buy a paid version, we use the free version to check how it works. It turns out that advertisements in categories can only be added from the admin panel.

PLEASE HELP AND CHECK THIS OUT

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