There are two different types of Instagram professional accounts:
Professional Business
Professional Creator
Because of the restrictions imposed by Instagram's API, attempting to post an Instagram Story to a Creator account will result in an error message stating: Error from Instagram: (#10) The user is not an Instagram Business. This is because only Professional Business accounts have the capability to directly post Instagram Stories.
How to switch your account to a Professional Business?
Visit your Instagram page on your web browser.
Click on Profile located on the left-hand side of the screen, then choose the Settings symbol.
Go to Settings and Privacy.
If you currently possess a Professional account you will see under the "For professionals" section on the left sidebar the option "Creator tools and controls".
If your Account is a Personal account you will need to switch to a professional account. Here is an article that can help you with that: Convert your personal account into a Business profile
5. Click on "Switch to business account".
6. Click on "Switch".