You need the Maxi PC Suite. You can download it here...
https://www.autel.com/download.jhtml
Once you have downloaded the software, you can login using your email and password. You can then do the software upgrade of your device through Maxi PC Suite. See this article for more information...
http://blog.autelsale.com/2017/07/06/update-autel-maxidiag-elite-md802-software/