Hello,
generally, Alfresco can track any kind of access via the Audit feature. Specifically, "download" is hard to track due to the different behaviors of the interfaces and clients, i.e. via HTTP or CIFS. I've tried to track and count downloads in my entry for last years Dashlet Challenge and had to admit defeat since I found no way to reliably count downloads without leaving at least one significant hole for false-positives that could mess up my counts.
I have seen a couple of simple implementations that rely on a custom download action in the Share UI to submit an AJAX call to a counting web script when the user hits "Download" before redirecting the client to the actual download URL. This works as long as you discount the option of users to cancel their download, either in a "Save or View" pop-up or while it is in progress. It just counts the number of times the action is clicked for that file. If that is sufficient for you and you don't need to consider other interfaces like CIFS or WebDAV, then this is an easy customization to do.
Regards
Axel
