Normally is the primary contact person for your company. You may assign your account / admin staff or other personas the secondary contact as below. You will have the right to login to view and update your company's billing info and view latest or passed invoices while secondary contact will recieve additional copy of invoices sent.
** Please fill in same contact name but with different email address under secondary contact info if you don't intend to assign other person to manage or follow up on your invoices. This is incase invoices didn't reach your primary email address, it will still reach secondary email address.