Software that creates a website with a catalog of different files to download?

Good day!

Let me explain what I need.
I have a folder, with about 30 subfolders, each of which contains hundreds of files.

What I want is to have a way (using either static HTML or PHP, I don't care as long as it's automated) to create a catalog of these files, with a download link.

I should end up with several sections, each named after each subfolder.
So if you click on the link to "A", you should see a link that is called as the file name and if you click there, you go to a download page for that file (or the file itself).

Any ideas???

BTW, I'm looking for something integrated into the website itself.
The only example that I could find of something similar to what I'm looking for (in presentation, not content, we'll be using it at our college for educational purposes).
http://megagames.com/games/fixes/all/J

You can select a different letter (which would be a subfolder) and go from there.

So basically, you want software like jAlbum but for files, not photos, right?