The screenshot of OpenScad model ended up at the end of the code. Here it is again:

4 small cable ties can be used to secure the adapter to the fan grill on the Apollo. But it can also just sit on top loosely.

The Noctua 200mm fan comes with a splitter cable that can be used to power the Noctua at it's full 800rpm while the 90mm fan is running with pwm variable speed.