Hi,
I cannot give you a definitive answer. But the transformer you specified appears to be for halogen lighting. There is no reason to believe the output is pure DC. It could be (and probably is) some type of AC waveform. I ran into a different brand of halogen lighting transformer some time ago and the output was not even close to DC**.
Now I expect you might ask how to convert the output from whatever it is to DC. I can guess but I would really have to know more about the actual output waveform.
** the 9V battery is pure DC and the Uno requires (almost) pure DC.