Wire the 3 modules per the schematic. Wireing is not critial. The relay is optional depending on what you want to do when a LiTz signal has been recevied.

You might want to use the relay to trigger an external alert or just pass the audio from the radio to a speaker.

Not very well documented in the schematic, the switch between d6 and vcc is a reset. Once the Litz triggers the relay, the pressing the button will reset the Litz/relay state

Load arduio code from the files section to your arduino and test.