How to see PDF files on my Samsung smartphone?

I have a Samsung Galaxy smartphone, it's configured in Dutch. When I want to see a PDF file, saved in my Downloads directory, it asks me which app to use, on which I choose "PDF-lezer", but it says to modify "machtiging" in "opslag" related configurations. Ok, this means that I need to open the configuration, go to app-configuration, choose the "PDF-lezer" app, and modify the corresponding "Machtiging" (permission) about "Opslag" (local saving). Problem: the "PDF-lezer" does not appear in the list of apps, there is nothing like "PDF..." in the app list. Question: how can I allow "PDF-lezer" to access files stored locally on my smartphone?