Topic Name : Activating the License
Publication Name : Installing vRealize Network Insight
Product/Version : VMware vRealize Network Insight/3.8
Can I activate the platform VM in trial first?
Yes, you will activate the Platform before adding the Proxy. After deploying the platform ova, power on and run 'setup' from the console. After the setup wizard is complete, follow the steps in the link you provided to activate vRNI.