please follow this guide.
Your Instagram account is not a business account
To be able to use the Connect Instagram business account your account needs to be an Instagram business account and not a personal Instagram account.
To change to a business account, please read this guide from Instagram
Your Instagram account is not connected to a Facebook business page
To connect your Instagram business account with a Facebook business page, please follow this tutorial
The facebook account you try to log does not have admin rights for the Facebook business page.
To add an admin, ask an existing admin or page owner to follow this tutorial from facebook
The Facebook account is a Facebook business for your page
You can only connect with personal Facebook accounts, if your account is a Facebook business Manager you need to change Facebook account to one with an admin role.