Well known issue.
It is because Windows 7 has no native USB3 drivers on the install media and your NUC model has 4 USB3 ports only.
So if you have tried to install Windows 7 using a USB Flash Drive onto a system that only has USB 3.0 ports you might have found that you couldn’t get past the Language Select screen of the installer as your keyboard and mouse didn’t work. I recently had this problem when trying to install Win 7 onto my NUC6i5SYH .
The keyboard and mouse worked great in the BIOS, but as soon as the Windows 7 installation media loaded and I was presented with that familiar Language Select screen, I had no cursor, or keyboard. I tried a couple of other things, like grabbing an older PS/2 keyboard and connecting it via a PS/2 to USB adapter. Same problem. It was at this point I decided to start Googling my problem, and low and I behold I quickly discovered that Windows 7 does not have drivers for USB 3.0 built in. In fact, it doesn’t even know what to do with those ports once the BIOS hands over control to the installer image.
(and many other sites offer a similar solution. I found this one working and easy.
Don't bother wasting your time with Intel's USB media creation tool, it's not working.
I was able to get it installed using Hausmeister99's link that was provided. A little down that page is a post by someone named det_bradlee. Used their procedure and I was able to get everything loaded. I first had to use BurnAware_Free to convert my DVD copy of Win7Pro to an ISO. After I had the ISO I was able to use RUFUS to make a bootable thumb drive from the ISO. After I had the bootable thumb drive I was able to pull the Install.WIM and Boot.WIM files off of there and inject the USB3.0 drivers into the Windows 7 installation files. Windows is installed but now I need a lot of drivers.
Thank you everyone for your help!!
Glad to help