Hello,
From your configuration I better understand the situation, you have 2 possibilities :
1. You want a search by product name, then the filter type text is most relevant
2. For search per categories then single (or Multiple) dropdown
For each case, I have create a filter in your backend AND associated each of the filter to your filter module in order to allow you to process some tests and better understand the filter use.
And as it seems that you want have filter only in Drenge parent category then maybe the most relevant is display this module only when your are in the Drenge category item menu.
I didn't save this parameter (like previous filters configuration) in order to don't disorient you, and so as previous, the filter module is displayed everywhere.
Hope this will help you to achieved what you need.
Regards