Follow these steps to configure Instagram for Social Poster.
Your Facebook/Instagram App does not require review and approval by Facebook/Instagram to use Social Poster.
In order to post to Instagram, you must ensure the following:
Your Instagram account is set to "Business" and not "Creator".
Your Instagram account is linked to a Facebook page.
You configure the Image Field for Post setting for an account.
Posts have an asset in the nominated image field. This asset must have a public URL, and cannot be a locally served-asset in order for Instagram to retrieve it.
If you already have a personal account on Instagram, you can easily convert it to a business account. An Instagram Business account is required to post.