This app is for use with the game GoKart - New Mexico - running in the same local network (as your iPhone wifi). The app turns your iPhone into a car driving controller where the steering input is done reading accelerometers while gas and brake are continuous controls through the touch screen. Some other buttons are available.
The free Demo version of the games for Windows and Mac to use with this app - are available here:

https://mobiletvgames.itch.io/gokartnm
https://gamejolt.com/games/GoKartNM/675761

For the app to offer the connect button on the starting screen the instance of the game (GoKart New Mexico) has to be running (on Windows or Mac computer) in the same local network as the wifi of the cellphone is using. The game is broadcasting its game host info which the app captures and creates the connect button. In case more than one instance of the game is running in the local network - more connect buttons will be offered for connection.