You can download it from
http://www.asustor.com/service/downloads?product_id=34
About Download Assistant:
Remotely manage download tasks
ASUSTOR Download Assistant allows you to connect to multiple NAS devices and manage all the download tasks for each device.
Supported operating systems: Mac OS X 10.6 onwards; Windows XP, Vista, 7, 8, 10, Server 2003/ 2008/ 2012
