MIXVIBES Dj Community old forum

I've just purchased Key Detect to find the keys of songs from my Spotify playlist. I know it should be easy and intuitive, but I can't see how it works. Where are the instructions? I'm using it to pair my guitar music with appropriate songs from Spotify. Any assistance would be very welcome.

It uses the phone microphone to listen to a music source (which cannot be the very same phone). If it doesn't recognize the music there must be something wrong with the audio input setting in the phone.