This is my first module (based on Wfdownload ;)... if you search simple docmanager module you can testing it, there are all features of Wfdownload and more.
I have add category for preferences module and others option (mime type extension with gif.., see your document, 90% css style using.. etc.)
But it's only french version.. you can rename french folder in english for testing please.
WARNING !! Don't distribute this version on web.. wait some week, because I haven't yet permission for using this module on the web..