There is no minimum number of followers required for businesses to use the Instagram for business service. To maximize the value provided by the Instagram for business service, businesses can grow their follower base. Doing so will likely result in more users contacting the business through Instagram in order to have their customer care needs met. Additionally, businesses will be able to provide more customers with product related information by using the Instagram for business service.
Learn more about the Sinch Messenger API for Instagram.