Can't download driver for Windows8.1

> [...] my PC can't download driver. [...]

   "Windows can't find" and "PC can't download" are spelled differently
for a reason.

> Please teach me how to install and setup.

   Here's a radical concept which works for some people:

      https://en.wikipedia.org/wiki/RTFM

   Visit http://netgear.com/support , put in your model number, and look
for Documentation.  Get the User Manual (at least).  Read.  Under
Downloads, nearby, there seems to be a kit, and its Release Notes
mention:

      Win 7/8/10 32/64 bits driver version: 1030.25.0701.2017
      Windows 7/8/10 32/64 bit genie utility version: 1.0.0.15

I'd try that.

You have posted your message in the section of this community given over to Nighthawk WiFi Routers. (This is easily done, given Netgear's impenetrable community structure.)

You might get more help, and find earlier questions and answers about your hardware, in the appropriate section for your device. That's probably here:

WiFi Adapters - NETGEAR Communities

Visit the support pages:

Support | NETGEAR

Feed in your model number and check the documentation for your hardware.

That page will also have any software, firmware and drivers for your device.

This might have a few useful tips:

Troubleshooting - USB adapter not detected | Answer | NETGEAR Support