To use an Instagram profile for promoting your brand with Ads Manager, you should add it to the business page of the advertised brand on Facebook.
To do this, the page administrator should open the brand page, go to Settings – Instagram and log in to the Instagram account:
An Instagram account can only be connected with one page. Likewise, a page can only have one Instagram account linked to it.
When the link between the page and the Instagram account is successfully created, you will see the account data in this section: