This project is Android's client side program. Computer's server side program can be found at: https://github.com/songhoseok2/PC_controller_desktop_app
Android APK of the app is located at: https://github.com/songhoseok2/PC_controller/tree/master/app/build/outputs/apk/debug
To find out the IP address of the Windows computer for the connection, run the command prompt of the computer. Then, enter the command: "ipconfig". The address displayed next to the IPv4 is the IP address to enter in the app. NOTE: this works when the Android device and the computer is connected to the same network (the IPv4 is the local network address). To connect from an external network, port forwarding will be required.
If the Arrow keys don't work, try disabling the Num Lock beforehand.