1. 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
2. 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
3. The Facebook account you try to log in with 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
4. 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 your Facebook account to one with an admin role.
This might seem weird since you're the business manager of the account but this is how Meta manages accesses to the accounts.
The user (private facebook account) who connects the company page must be added as "People with Facebook access".
Add the user here when logged in to the Business Facebook page: https://www.facebook.com/settings/?tab=profile_access
If these suggestions don't solve your connection, please reach out via chat or email at info@cevoid.com, and we will assist you further.