How to open access to wifi Internet for an action?

Question

Computer networks

There is a cafe, it has a VK group and an application for mobile in the google store
Tell me how to implement the technical part so that when visitors enter through the wifi of the cafe, the Internet is provided only after installing the application and subscribing to the group? Well, the light option is when it is simply proposed to do these actions, but the Internet still remains. It is necessary to understand exactly the technical implementation of how to close the Internet and how to open it later after the necessary actions?

Answer 1

Captive portal + vk oauth - google