An administrator needs to manually install the Symantec Management Agent using an install package.
Release: 8.5, 8.6
After obtaining the install file, right-click it and install it as Administrator.
Here are the methods to obtain the install file:
Go to the following URL to download the proper package: http://NotificationServerName/DomainName/Altiris/NS/Agent/AltirisAgentDownload.aspx and click on the link to download the install file.
On your Notification Server go to [Install Drive]:\Program Files\Altiris\Notification Server\NSCap\bin\Win32\X86 and download "AeXNSCHTTPs"