Successfully connected the web page with the Facebook app + Facebook page. When commenting on a post the comment and the post appears on the FB page. But no FB posts. All permissions granted, registration of users in setting allowed. (support access active).
This discussion started separately as suggested in "FACEBOOK LOGIN AND FB POSTS NOT WORKING" discussion (https://premium.wpmudev.org/forums/topic/facebook-login-and-fb-posts-not-working?replies=9#post-1144120).