NSX-V does not have a trial available, that's why you can't access it.
Even if you got the source file from any one you cannot prepare the host or install the nsx agent on the esxi host without licenses.
If you want to study or learn more you can use VMware HOL VMware Learning Platform
Thanks for your inputs and sharing of your experience. Very well.
Will NSX-V work under Nest ESXi host environment for lab or testing purpose?
Assuming I have all license VMware for NSX-V, vSphere ..etc, will this work in one esxi bare metal ?
I built my NSX-V LAB on PC machine with 64 GB RAM using VMware workstation. you can find the details in my blog Building NSX-V LAB - MF blog and you can also find the how to to implement the NSX-V environment How To install and configure NSX-V 6.4 - Part 1 - MF blog . try to use the minimum resources of the Virtual appliances and machines.