I tried loading the same file, and I also got an empty screen. Something must be missing or different in the structure of this file, but I doubt if any of us can determine exactly what's wrong.
I'd try to look for an alternative KML file with the same information - typically, there are many alternative sources of the same geographical data.
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I checked in various systems, not only Qlik, and could not open it anywhere, except Google Earth.
Maybe Google Earth has the parser, which ignores some mistakes and continue read what is good, while other systems just ignore this kml facing the error.
Please check this thread, also related to Belgium kmls Cannot load a kml file in Sense | Qlik Community for some insight.
If you have list of cities, which are administrative centers in this province, I can get you the coordinates of it (so called geocoding).
I've found that point maps work much better and more visually appeling than polygon ones.
Also you can find some beautiful mapping extensions on the branch.qlik, based on Google maps or ESRI or Openstreetmap
Check this cool demo - https://www.youtube.com/watch?v=MbBanVtwwGo
this is very easy to reproduce in QS.