Once you have downloaded the image, you can verify it by checking against the relevant SHA256 digest.
Oracle Solaris 11.4 VM Template for Oracle VM for SPARC
This guest domain can be installed on any system running Oracle VM Server for SPARC 3.1.1 or later under the control of Oracle VM Manager 3.3.1. The administrator configures the guest domain template (name, IP address, etc.) during the first boot.