I have the exact same question. My web service is setup correctly, and I can access my LinkStation from the outer side of my router.
What I wanted to do was to give my family access to my files - AND download them. Unfortunately it is not possible to download the files, which makes the LinkStation more or less useless.
Other user can open, rename, or delete a file, as well as create a folder and upload a file. HOW DO THEY DOWNLOAD ???
If have some mp3 files on my LinkStation, and the only way to download them is to click "Open". If no media player is installed on the users PC (actually, no installed programs have a mp3 file association), Windows offers the option to Save the file to disk.
If f.ex. Windows Media player is installed, it just buffers the file and starts playing.
Once again: How do my family and other people download from my LinkStation ???
/Glenn