You can try it in Vmware HOL (HOL-1729-SDC-1)
Try to use the VMware Software Manager to download vRNI.
It's available under Infrastructure & Operations Management, see below screenshot
Not sure if this is available for everyone or vExperts only, but you're vExpert anyway.
Not the latest version but at least you can have vRNI on your environmentBayu Wibowo | vExpert NSX, VCIX6-DCV/NV, Cisco Champion, AWS-SAA
Author of VMware NSX Cookbook http://bit.ly/NSXCookbook
https://nz.linkedin.com/in/bayupw | twitter @bayupw