The ART TubeMP is a Mic preamp, so it outputs 'line-level'. So you shouldn't plug that into the microphone input.
That said, the microphone input should get a signal (although too loud and/or distorted).
If you have a line-in on your pc, use that. Or a line-input on your USB sound card, of course.
(Also, to exclude issues with the docking station, try to make it work first by connecting it to the pc directly.)
If you get nothing out of the preamp, regardless of input and output gain settings, chances are that you haven't enabled the 'P-Pwr' +48 volt phantom power that the condenser microphone needs to operate. (connect mic and turn down volumes/gains before switching it on..)
You could test the preamp by connecting the output to a hifi amp, headphone amp or mixing desk and see if you can get a signal out of the microphone.
Good luck!