Yes, your customer can download a downloadable item at "MyPage > Purchase History".
Once your customer buys any item at your "ONLINE-CATALOGUE", the column of "Purchase History" is automatically generated in the customer's "MyPage" at your "ONLINE-CATALOGUE".
At the column of "Purchase History", all receipts are displayed.
When your customer buys a downloadable item, the "DOWNLOAD"-button is automatically displayed under the name of the purchased downloadable item. See the screenshot below. Your customer can download at the red-circled place in the screenshot.
When your customer clicks the "DOWNLOAD"-button at the red-circled place above, the new window is displayed. On the new window, the input-bar of the domain which your customer will install the item is displayed. Your customer can download the downloadable item without inputting the domain, but, according to your upgrade-policy, your customer can't download the upgraded-version of the downloadable item at the same receipt.
By clicking the "DOWNLOAD" button at the window, one more new window is displayed. On the new window, the information like checksum, license which you set at your "Rainbow-Link Control Panel" are displayed. If your customer click the "DOWNLOAD"-button under the informations, your customer can download the downloadable item to the customer's machine.