The Twin Turbofan is made to fit the stock CR-10/Ender 3 (MK8/MK10) hotend and the stock heat sink cooling fan. It simply requires two 5015 fans, four M3 x 20mm as well as four M4 x 20mm button head screws and one M3 x 8mm screw (preferably socket head). It also requires 4 M4 Nuts (preferably thin - approximately 2mm depth).
Default orientation of the STLs is best for printing.
RADIAL FAN BRACKET:
The actual fan bracket/fang is a very complicated part and should be printed solid as this is a structural part that needs to be strong.
PETG or ABS are your best options due to the fangs being so close to the hotend but PLA can be used. I actually printed mine in eSUN PLA+ as that's all I had at the time and it still works fine but if I had the option I would definitely use PETG.
Supports are definitely required and i found that Cura's experimental tree supports with a branch angle of 40 degrees worked quite well as they all attach to the print bed and not lower areas of the part (this could probably also be achieved…