The version of Sophos Anti-Virus for Linux you can use depends on your management console.
Sophos Central managed computers
For 64-bit Linux computers you use Sophos Anti-Virus for Linux version 10.
Standalone and Sophos Enterprise Console managed computers
You can only use Sophos Anti-Virus for Linux version 9.
To install Sophos Anti-Virus so that it is managed by Sophos Enterprise Console, see the startup guide for Linux and UNIX on the Sophos Enterprise Console page.