Hi there,
Ok , so I looked on the app here and reconnected up to the kit I have configured… I see Notification on Alert/bell receipt. that and the correct GPIO and Bob’s your Uncle I’m thinking…
here what I see…
Paired devices earlier are still in app, pick the S3 and wait for Green LED and good connection.
Go to radio configuration, scroll down to Module configuration and pick external Notifications…
I think you can Land it from here… LMK
Notifications on Alert/bell RECEIPT
Pick the GPIO you use …
HTH
GL 
PJ
FYI it works both ways… 
The Pro Move is Sending a message back and clearing the Status or Trigger if you’re Flexing 
“Notification on Message” pick your GPIO once again , ROBERT is your Uncle… 