Unable to connect to Facebook Messenger

Brother use your ngrok url: https://13bcfd61e6cd.ngrok.io/webhooks/facebook/webhook/

If your url is working fine then why are you changing it. I used xxxxxxxxxx just for reference.

Have you tested your messanger after you get the success status 200 ok

Note when your app is in development mode

Only admin, developer and tester can get messages from chatbot

You can this in Roles section of your fb app