Facebook Messenger API talks to RedBot via a https callback (a self signed certificate is not enough). We’ll use ngrok to create a https tunnel for our local Node-RED instance. Install it, then open a shell window and run

ngrok http 127.0.0.1:1880

You should get something like

ngrok

Grab the https address you get, something like https://123123.ngrok.io, this is the base url that points back to your Node-RED instance.

The callback is

<http://youraddress.ngrok.io/redbot/facebook>

Replace the hostname (youraddress.ngrok.io) with what you got above. Start here to create a new Facebook app, select type None.

In the app Dashboard go to the “Add products to your app” and add Messenger