These instructions are for installing antivirus software in an unmanaged environment from the Supported Products article.
Caution: Please remove all antivirus programs before installing this product; this includes removing older versions of Norton Antivirus for Macintosh or Symantec Endpoint for Windows.
After accepting the licensing agreement, the file will automatically unzip and place an installer in your default download location (probably your Downloads folder located in the Apple Dock). Double-click the installer icon and follow the on-screen instructions accepting the defaults. After you finish, you can delete the installer by dragging it to the Trash.
Note: After the Penn installer completes, the Sophos Home installer program will run. Follow Sophos Home on-screen instructions to finish installing the software. Both installers are needed to provide all components needed to protect your machine. The installation will take several minutes.
After you accept the licensing agreement, follow the on-screen instructions to install the software. After you finish, you can delete the installation file.
Note: Internet Explorer users may need to append .exe to the filename after downloading Sophos Home to the desktop: in the "Save As" window, create or go to the directory in which you want to save the file, append .exe to the file name if it is not already there, and click Save. Open this directory, double-click the installation file.