I printed it with 30% infill but will probably work also with less, default settings in the rest, no supports needed.
Do let me know if it turned out ok :D.
The author remixed this model.
I have taken the CZFA_FlexFrame_PhoneMount.stl and modified it to be a headset hanger.
For the required files for the arm, they can be found here https://www.printables.com/model/647794-flexible-sturdy-phone-arm-100-printed/files .
Do note for the screws to reduce them to 99% (saw it worked great for me when doing that).