Unfortunately, the error message is really not enough informative for each case. This is a general error message appearing when a certain quota (or feature) for an account is not enabled.
The reason for the error in this particular case is that the Social User Management with Telerik Backend Services is not included in your Telerik Platform subscription
plan. This feature is enabled in the Telerik Platform Professional or higher tier subscription plans and also comes with each newly-created trial account in the Telerik Platform.
In regard to implementing Facebook sharing and posting in a hybrid app built with AppBuilder one good approach might be to consider using the SocialSharing-PhoneGap-Plugin.
Please, let us know if you have further questions.
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