If they are in ONE folder, I have to rename ALL 700 files, in order to find them. And then they would became very long filenames.
There are files named guidelines for example. Every different system has a guideline and there are actually about 50 different systems, so I think the folder structure as it is would be the best!
That's not it though? In App, as described by Patryk, you can have a single List View that first displays a Master List, from which a sub list would be selected and displayed in the same List View. When you pick any item in a Sub List, a more verbose description of the item can be displayed, so that the User can then decide if they want to read more, make another choice or just exit.
Updates often need the App to be updated. However, if your are able to craft your CSV into Categories and subcategories that could mean no change to the App - it only uses a single List View Component, which lists what you want it to list at any given time. No folders required in the ASD, just the files.
You can implement this File Explorer into your app. I adapted the paths to your ASD. It only displays pdf files and folders and is limited to the "kundc" folder, where you downloading folders and files to.
I was wondering if the File Explorer is also working below API 29, so I was testing it and it is only showing the folders, but not the pdf files in the folders!?
I do not have anything older than android 9, so I will not test it. If the Taifun extension works on older phones then it must work. Maybe read permissions are still needed on older phones, even for ASD !?
READ / WRITE permissions are not required for the ASD since API 19. However, these permissions are requested and granted before API 23 at install-time (and not at run-time). Since the TaifunFile extension declares these permissions in the Manifest, there should be no problems.