To link an Instagram Business account with a Facebook page, you should have the role of admin or editor.
✎ To find out your role, open a Facebook page > Tap ‘Settings’ at the top of your page > Tap 'Page Roles' in the left column.
✎ If you are the owner of a page, then assign a role to your team member:
Settings > Page Roles > Enter a name or email, select a person from the list > Editor or Admin > Tap ‘Add’, then enter the password to confirm the action.
✎ If this person is not your friend, it is required to accept the invitation to manage your page.