Kali Linux's NVIDIA driver install guide does not work

Question

I'm trying to get my natively installed Kali Linux distro to detect my second monitor. I have two Samsung S20B300 monitors but its only picking up one of them. The one it is picking up is plugged in via DVI. The one that it is not is plugged in HDMI on the computer and DVI on the monitor (I have a HDMI-DVI adapter). I know the issue is not with the monitors themselves because my dual boot windows detects both monitors.

I figured the likely culprit was that I didn't have the proprietary NVIDIA drivers downloaded. So I followed the official guide to installing them except when I got to the last step of calling glxinfo to see if it worked, I got the output

Xlib:  extension "GLX" missing on display ":0.0".
Xlib:  extension "GLX" missing on display ":0.0".
Xlib:  extension "GLX" missing on display ":0.0".
Xlib:  extension "GLX" missing on display ":0.0".
Xlib:  extension "GLX" missing on display ":0.0".
Error: couldn't find RGB GLX visual or fbconfig
Xlib:  extension "GLX" missing on display ":0.0".
Xlib:  extension "GLX" missing on display ":0.0".
Xlib:  extension "GLX" missing on display ":0.0".
Xlib:  extension "GLX" missing on display ":0.0".
Xlib:  extension "GLX" missing on display ":0.0".
Xlib:  extension "GLX" missing on display ":0.0".

And have no idea why. Obviously something didn't work because my second monitor still is not being detected either. I'm running a custom PC with an Intel Core i5 4690K processor and NVIDIA GTX960 GPU