I should clarify, I need to know what the origin of your footage was. Is your original quicktime looking fine but then rendering out dark or is it dark to begin with? Is your monitor calibrated to for a specific color group?
I don’t think your color is cineon because cineon is a white washed grey color.
So, change the output in color converter to the right color output like “example. Apple RGB” (Find out what the origin of the original color management was!)
as for the codec, 10 bit 4:2:2 codecs of windows and macs are still, compression-wise, the same, just the colors aren’t exact. Color manage it through workflow and keep track of what they are encoded at. Professionals leave most things at ProPhoto RGB because the colors don’t change from computer to computer or windows to mac, with properly calibrated monitors.