You must use an administrator account on the Macs that you want to protect.
To protect Macs:
On each Mac that you want to protect, browse to the bootstrap location. Copy
the Sophos Installer.app installer file and the
Sophos Installer Components directory to a preferred
location (for example, the Desktop) and double-click it.
A wizard guides you through installation.
Accept the default options. When prompted, enter the details of a user account that can install
software on the Mac.