The bike rack is designed to clamp the frame via the top tube this way, but I’ve heard that it’s not a good idea to clamp the top tube as it’s designed to be so. The clamp itself is designed to ‘click’ after certain amount of torque, similar to a torque wrench.
The bike rack itself is a one by THULE, not sure which exact model it is, but if you have had any experience with it feel free to share them.
by Just_Dank