Because Yin Yoga is a functional yoga practice and not an aesthetic yoga practice, targeting different areas in your body is more important than trying to "master" a pose.
When targeting the glutes, some people get their best access through the pose of sleeping swan.
Some prefer deer pose, whilst others might prefer shoelace.
This video below gives you some options to try so that you can find the shape that is a good fit for you to target your glutes, rather than forcing your body into a yoga posture that is painful or even injurious.