Exactly 6 months ago (August 1, 2018) Facebook closed unrestricted access to its official API.
Several hours later they backed down and gave all API users 6 more months to obtain app approvals.
Six months passed and, as promised, today (February 1, 2019) they closed unrestricted access to its official API again. Looks like this time it will stay closed. From now on, only approved apps will be able to autopost.
If you try to post to Facebook with unapproved app you will get this error:
There are two options.
More info about what happened with Facebook.