RTL 8812AU driver error and Dual Boot

[drp412]

I have successfully installed macOS on my other partition of El Capitan and working great. But I have few problems like;

I have USB wifi stick having RTL 8812 chipset (Premiertek PT-8812AU) and I tired to installed driver but still I can't able to install on macOS. When I tried to install from installer package, all options are not highlighted so I can not able to install. But as soon as I boot in to El Capitan, It is working great in El Capitan. How do I fix?

Other, I have dual screen problem. Now my both El Capitan and macOs stopped working on dual screen. I am using 14.2 ( iMac (27-inch, Late 2013)) under about my Mac, it was showing me my graphic card, i.e. EVGA Geforce GTX970 o mb. How do fix this too? I searched the forum and tried all bootflags but still no luck.

Any help..