Instagram Set Up Help -- 2

Need help setting up client account I now manage. I have all the approvals in place but the only element missing is the ability to post on their behalf. I have full control over their account. I set up another client recently and it works perfectly. With this new client, the button with the plus sign in the middle (post button) is not available.

When I go back to reviewing the connection, the last panel asks me to confirm the connection but the confirm button is faded out. As far as I can see, I have done everything correctly. I'm absolutely puzzled.