USB/BT Joystick Center
You’ve stumbled across the very outdated documentation for the USB/BT Joystick Center 6 Android App.
This app is long since abandoned by the developer, and you need to get a license key from his server to use it.
I don’t believe the licensing server is still running.
Building This Documentation
You need to use the
publican toolchain. It is only available on the Fedora OS (if you want a supported version).