the case uses this heat sink :
https://smile.amazon.com/gp/product/B07Z3Q417K 

I used :

4 - m2.5 x 8mm screws to attach the back

4 - short standoffs that came with the heat sink kit

4 - m2.5 x 6mm screws to attach the top

I removed the plug end from the fan and put heat shrink on the wire ends to insulate them, so plugging the fan doesn’t bend the pins in the pi header.  
 

The heat sink interferes with the disconnect for the camera cable. if you want to connect a camera to the pi, you will need to attach the cable before you assemble the case. A bit of a pain, but hey.