The author remixed this model.
This is identical to the original, other than the extruded circle which goes down to the Fan, is 0.5mm shorter as the case would not close. Now a perfect fit.
The original circle extrusion sat on top of the fan and actually caused the plastic to bend, if you tried to hold the case closed. When you let go, the white section of the RPi5 case would partially pop open.
Removing 0.5mm from this circle extrusion, gave the required clearance, and now its a perfect fit to the top of the Fan.
I am unsure if something changed with the active cooler, and they supplied 2 different thickness thermal pads or something, causing this variance, but this was the solution for mine.