More information about Windows ARM support for Symantec Endpoint Protection and Symantec Endpoint Security.
Starting with SEP 14.5, the Windows ARM agent can be managed by a 14.5 Symantec Endpoint Protection Manager.
SEP 14.3 RU7 through 14.4 versions of the Windows ARM agent have the capability to be cloud-managed (SES) or function as an unmanaged agent (on-prem, SEP)
The unmanaged package (if desired) is available as part of the Full_Installation download of SEP:
For cloud-managed, you may choose the Windows ARM architecture when downloading the SES package: