How can I send a pop-up notification to my page on ESP-01 when connected to wifi (as an access point) from my phone?

Question

Arduino

Good afternoon,
Recently, while skimming through the news, I saw a short video of how a person from a mobile phone connects to wifi on the machine (ESP8266 is responsible for the distribution), he pops up a notification about connecting to wifi (like registering a subscriber at airports and now cafes), he clicks on it and enters into one page menu for opening the door, which actually demonstrates.
The question is:
How to make the ESP-01 or a more advanced version (if there is not enough memory) send a notification to an internal web page with a button when connected to it?

Answer 1

Most likely, the phone itself checked the Internet connection and if it did not find it, it redirected to the setting page of the router (esp). As far as I know, this has not yet been implemented on esp itself (I could be wrong)
Here is an example of how to set up a redirect to an internal page when entering any site.