Looking for relative in Kansas

Hello! We recently found out, with my Aunt's passing, that she gave up a daughter for adoption in Kansas in either 1969 or 1970. We only have the name of the adoption agency and nothing else. No exact birth date or place of birth. I have done internet searches of my Aunt's name in various adoption forums and have come up empty handed. I keep reading that Kansas is an open state. Does this mean if my cousins contact the agency, they will release her files? What else should we do to help start looking? We would love to find our long lost family member!!