CS-Cart supports downloadable products by default.
When a customer purchases a downloadable product, an email with a download link is sent to the customer. Before the customer could get the access to a download page, the administrator should switch the order status to 'Processed' or 'Completed' in CS-Cart admin panel. After it is done, CS-Cart will send an email to the customer with a link inside where the customer will be able to download the purchased software. This link contains secure key which saves download page from unauthorized access.