If your Facebook Group posts are failing and you're getting error #200 on your failed posts, then this is due to an update by Facebook from 2018.
In order to proceed with posting, you (as Group admin) must add the StoryChief app to the Group settings. This is a one time process that will allow StoryChief to post to a Facebook Group on your behalf.
Take the steps below to add the app to your Facebook Group.
1. Add the StoryChief app in your Group settings
On Facebook, navigate to the Facebook Group you want to publish to with StoryChief
Scroll down and click Settings on the bottom left
Scroll down to "Apps" on the bottom right and click the pencil "edit" icon
Click the blue Add Apps button on the popup that appears
Type StoryChief in the search field and select it
Click the Add button