While the storage controller supports SNMPv3 OnCommand System Manager 3.1.3 does not support the use of SNMPv3 to add or discover the controllers. Reference the release notes for OnCommand.
OnCommand System Manager 3.1.3
Release Notes
https://library.netapp.com/ecm/ecm_download_file/ECMLP2602644
Page 26: System Manager only supports SNMPv1 and SNMPv2. You cannot use System Manager to discover or add clusters through SNMPv3