It seems that you are not on the verified partners' list to post on Instagram:
https://www.facebook.com/business/partner-directory/search?solution_type=community_management&ref=pd_home_hero_cta

Some others like Buffer, Later and I think perhaps Publer are all on the list but I do not see you.
I am a bit concerned with this, can you please comment and let me know if on your roadmap you plan on getting verified?
I am using a side tool that needs verified partner posts on Instagram and so that is why I ask.

Thanks.