Older ova files have old OmniOS releases out of support with unfixed security problems.
You may update but propably it is easier to install manually:
upload a current OmniOS installer iso to Esxi
create a new VM (30 GB, type Solaris 11, boot from installer iso)
add/use a vmxnet3 vnic for best performance
after setup, set nic to dhcp or set nic manually, see
napp-it // webbased ZFS NAS/SAN appliance for OmniOS, OpenIndiana and Solaris : OmniOS
reboot, Open-VM tools are already included
run a System > Tuning for best 10G performance on vmxnet3
Install napp-it via wget