I am confused - sounds like you installed osCommerce if you got that far. If not sure of paths, get FTP access from the client, ask for full priviledges and allow you access to the document root. Then go in there and look at the folder names, and create any you need with proper permissions based on help provided below as to path suggestions.
Here is a great link for help on setting up any item's Product Attribute, please read it fully if the help below does not help you. If those zip files (each is an archive) are to be unzipped and placed on the server for inclusion in your shop (i.e. the MP3 files) then create a folder within the osCommerce base directory called "music" and use the proper path in the Admin setup for each item.
Example of absolute paths (MOST COMMON SETUP):
Document root: /path_to/public_html (
http://www.yourdomain.com points here and runs index.html, index.php etc.)
Image path: /path_to/public_html/images
osCommerce base path: /path_to/public_html/shop (
http://www.yourdomain.com/shop for the store)
Music base path: /path_to/public_html/shop/music (contains all the MP3's organized, extract each .zip with folder names intact incase any subfolders exist)
Remember in osCommerce you should use relative paths, i.e. "/shop/music" or "/shop/music/p/pink_floyd_dsotm.mp3" - get the idea?
If for security reasons you install "music" above your document root, use the absolute base path instead.
Is this what you're asking? Hope this helps ya.
-jim