Can't Connect Private Instagram
There is a known bug on Facebook where users get this error when trying to add Private Instagram or Facebook connection {"error_type": "OAuthException", "code": 400, "error_message": "Your account is connected to Facebook account, and your Facebook account's future off-facebook activity is currently turned off."}
This is because Facebook checks for Off-Facebook Activity settings, and this is by Facebook's security design. It to resolve that, you or your team's Facebook Future Off-Facebook Activity settings must be turned on.
Here's a quick guide on how to turn it on