Cannot setup the FB messenger

I cannot setup my abandoned cart recovery, i’ve done everything from your guide, seems your guide is outdated and the facebook developers dashboard has been changed, one of the facebook team ask me this like a test message after requesting.

“This is a test message from the Facebook team. Please respond from your app within 2 days to confirm that the integration is functioning.”

also I cannot get to work with the button on after the “add to cart” button where the messenger resides