Getting bluetooth MIDI working is different on iOS and Android, the instructions to do it for each are below.
iOS
On iOS you must use Koala’s “Bluetooth MIDI” button to connect to your device. Open settings, choose “MIDI” from the top and press the CONNECT button next to where it says “Bluetooth MIDI” and add your device.
Android
All you need to do on Android is to pair your bluetooth midi device with your phone as per the instructions for the manufacturer of your device, the rest should be automatic. THERE IS NO BLUETOOTH MIDI BUTTON ON ANDROID, ITS NOT NEEDED!!!!