you have to enable the developer option on your device. Go to settings, then navigate to the “Build number” (for example: Settings > About phone > Build number).
then tap 7 times on tap on the section. After the 7 taps, the Developer options will be unlocked and available.
That is more or less all you have to do. Then connect your phone to the usb and start b4a. Run your app and it will apear on your device