Hi,
It can be downloaded from Flexnet & you need different licensing or contact reseller to see if there is any product bundling.
The use of the Symantec AntiVirus or Symantec Endpoint client to scan drives on a NAS device is not recommended and is not supported.
Recommended product: Symantec Protection Engine for Network Attached Storage
Symantec Protection Engine for Network Attached Storage provides scalable, high-performance threat detection services. These services protect valuable data stored on network attached storage (NAS) devices, providing increased scanning performance and improved detection capabilities for protection against multi-blended threats. Protection Engine includes Symantec's industry-leading malware protection for fast, scalable, and reliable content scanning services. These help organizations protect their data and storage systems against the ever-growing malware threat landscape. Malware definitions and engines are updated automatically with no interruption in malware scanning using Symantec LiveUpdate. Definitions can also be distributed centrally to multiple deployments utilizing the included Symantec LiveUpdate Administrator application.
Similar threads:
https://www-secure.symantec.com/connect/forums/will-sep-121-be-able-scan-partions-carved-out-nassan
https://www-secure.symantec.com/connect/forums/different-between-symantec-endpoint-protection-and-symantec-scan-engine