If you want your Instagram ads to be published with your official Instagram account, then you need to claim your Instagram account in your Business Manager. You are able to set the Instagram accounts that are promotable by a given ad account. These accounts will be selectable in our interface under the campaigns using that ad account.
Business Manager Settings > Instagram Accounts
Please note that you need to be the admin of the Business Manager to add a new IG account by following the steps below:
In Business Manager, navigate to your Business Manager Settings > Instagram Accounts.
Click the "Add" button and enter the login credentials of your Instagram account and click on Next.
3. Attach an ad account.
Keep in mind that this is an optional process. You can run Instagram ads even if you do not have an Instagram account for your business. In that case, your Instagram ads will be Facebook page backed.
What happens if the IG account is owned by another BM?
If the IG account you're trying to add is owned by another BM, you'll get an error which mentions that the account is already owned. If this is the case, there are two options that can be done to gain access to the IG account.
The first thing that can be done is to ask for partnership to the BM that owns the IG account. In order to do that, a person with admin access on the BM that owns the account should click on the "Assign Partner" button after finding the IG account in their own BM.
The second thing to do is to get in touch with the BM admins of the BM that owns the IG account (if the owner is known), asking them to remove the account and to add it to your own BM by following the steps mentioned above.