The Wi-Fi Control Gate App is an application that allows you to open a gate, lock or other type of drive using a relay module, an ESP-01 module and an arduino.
The ESP-01 is configured to connect to the local Wi-Fi network, where it receives the command from the APP and passes it on to the Arduino, which in turn activates a relay module with a pulse, activating the lock and releasing access.
In the video of the tutorial for using the APP, you have in your description the links of the sketch used and also a PDF file from ESPRESSIF, which is the manufacturer of ESP 8266 where everything has to do with the controller, including its AT commands and useful information.