How to organize limited Internet access on Wi-Fi?

Question

WiFi

Hello. Do not tell me how to implement the following:
A person in a cafe accesses the Internet via Wi-Fi and gets to the start page (which I did). And so that he can continue to access the Internet, he must enter a password.

Answer 1

A person "goes" (hmm) into a cafe on the Internet via Wi-Fi and gets on a regular WPA2-PSK network where he enters a password.
Why a separate page "what I made" and that's it?

Answer 2

Here