Go to your Facebook page, go to the Settings section (see screenshot below), go to the Advanced Messaging section and add your domain to the Whitelisted Domains list. Third-party domains that are accessible in the Messenger webview for use with the Messenger Extensions SDK, and for Messenger plugins.
Then go to the Messaging section above and add/enable Messenger for your website. Let people start a conversation on your website and continue it in Messenger with the Chat Plugin. It’s easy to set up, just follow the steps in the Get Started button.
In the last step of the Chat Plugin setup, you will see the CHOOSE AN OPTION TO INSTALL THE CODE. Select the “Email instructions to your developers” option and let us do the rest.
If you want to install it yourself, either use Google Tag Manager to add the code to your site or use the Facebook integration in Supernova.
You won’t need the code snippet provided by Facebook, you will only need your page ID.