If your image meets all of the required criteria for auto-posting, and you're still seeing a pop-up error message (as below), then this article will help!
This error message can be due to:
1. You having an incorrect role on the Facebook Business Page that's linked to your Instagram Business Profile.
The auto-posting feature can only be unlocked by the "Admin" or "Editor", and not by any other roles on the Facebook Page.
2. Insufficient permissions given to us via your Facebook Business Page - 'Create post in your Instagram account' needs to be checked. You can make sure you've agreed to all the correct permissions by clicking this link while logged into your personal Facebook account: https://www.facebook.com/settings?tab=applications and clicking on the Iconosquare app, as below.
3. Please note that if you've got several Instagram Business Profiles, you'll need to check these permissions on each of their individual connected Facebook Business Pages.
Tried everything and still can't auto-post? Click HERE for more advanced troubleshooting