Lee,
If you created upload Mashup then its just a few steps to get download to work.
Your Thing I expected used the Template of FileRepository (Which we will call MyRepo)
That things has Services you can use called GetDirectoryStructure which I expect you used. You can also use GetFileListingWithLinks. Wire the services up connecting selected rows path from the GetDirectoryStructure to Parameters of the GetFileListingWithLinks. From the UI you can use the Link in the Grid to download the file.
Note: In your File upload Mashup you would of set the RepositoryName to "MyRepo" in the FileUpload Widget which connects the Services to the UI
Hop this helps
