On the internet you can find instructions for this same Polo built between 2001-2008, according to which it should work. There should be space for a double DIN, because the original radio either has double height (if with CD player) or an empty compartment below the radio. What you have to get separately, however, is the right adapter for the analogue part of the radio, in the car it's ISO standard, but the Pioneer has DIN standard.
If I'm guessing correctly from the photos, the wiring harness should also fit the Pioneer.

Nevertheless, it is best to have the situation clarified by someone with some knowledge beforehand so that there are no unpleasant surprises.

Should fit who a large compartment is ok.