One of the things you will run into is that a standard Qlik Sense map cannot show more than 3333 polygons. Since there are more than 12.000 neighbourhoods you won't get a map that shows them all. I think you'll need a mapping extension like GeoQlik or Qlik GeoAnalytics
Also a lattitude, longitude dimension doesn't sound right for a KML file. I'd expect a geometry field instead of one lat./long. coordinate.
I've added a KML file with 389 unique areas including what I think are geometry fields: Gemeenten 2017 onbeveiligd.xlsx - Google Drive
When I add a map element to the dashboard however, this time it doesn't seem to show any of the dimensions I created (GM_CODE, GM_NAAM, KML).
I've also tried to arrange a trial version of GeoQlik and GeoAnalytics. Because we're a group of students we'll only use the extension for a singular project. Unfortunately none of the people we contacted seemed to have an trail account/code we can use for a week.
If you like you can try free version of SVG Maps.
For that you'd need 2 digit ISO codes for the areas you trying to load. SVG does have a preloaded Netherlands map but it is not on street or district level.
You have to find a .svg map for the areas on google.
Download SVG extension and try it for your self....
Or as Gysbert suggested, you'd have to get paid versions of GeoQlik or Qlik Maps.
I guess GeoQlik has free version as well... check their website