Open ArtRage (if not opened already) and tap your "S" key on your keyboard to toggle the "Color Samples Panel" on (the panel pictured below will appear on your screen, minus the red text).
Click on the black triangle (circled in red in the picture above) and select "load colors". Browse your way to the .col file you downloaded, select it and open it. The colors should now be shown within your Color Samples Panel for use.
To learn more about the different methods of selecting colors in ArtRage, please view my video here: LINK.
Nothing is easy to the unwilling.