foody ionic3 restaurant app by BrainSystems

This is my first purchase from envato - Foody Ionic 3 Restaurants App.
So I downloaded an app but how do I see it fully functional, what backend service should I use. Am i missing something or all those apps just UI part? I would think at least the schema of the store should be published somewhere.
Emailed the company twice asking the question but unfortunately no reply.