Installing USB WiFi driver
This page will help you to install USB WiFi driver dongle on Debian/Ubuntu OS.
RTL8812AU
$ sudo apt update
$ sudo apt install rtl8821au-dkms linux-firmware
RTL8821AU
$ sudo apt update
$ sudo apt install rtl8821au-dkms linux-firmware
Hardkernel's Wifi Module 5A
RTL8821CU
$ sudo apt update
$ sudo apt install rtl8821cu-dkms linux-firmware
Hardkernel's Wifi Module 5B