Don't choose QUBE.exe in the main directory, go instead to
Screenshots without HUD can be made with Nvidia Ansel at least. Press Alt+F2 ingame. Note that there is a bug resulting in the circle in the middle of the screen being displayed in certain instances, such as taking a screenshot in super resolution. Only restarting the game will fix this. To make Ansel save as PNG, go to "C:\Program Files\NVIDIA Corporation\Ansel\Tools", and run NvCameraConfiguration.exe.