This driver can be installed using [DKMS]. This is a system which will automatically recompile and install a kernel module when a new kernel gets installed or updated. To make use of DKMS, install the dkms package, which on Debian (based) systems is done like this:

sudo apt install dkms

In order to install the driver open a terminal in the directory with the source code and execute the following command:

sudo ./dkms-install.sh

In order to remove the driver from your system open a terminal in the directory with the source code and execute the following command:

sudo ./dkms-remove.sh

For building & installing the RTL8812AU driver with 'make' use

make
make install

and for building & installing the RTL8814AU driver with 'make' use

make RTL8814=1
make install RTL8814=1

Download

git clone https://github.com/aircrack-ng/rtl8812au.git
cd rtl*

To download v4.3.21

git clone -b v4.3.21 https://github.com/aircrack-ng/rtl8812au.git

Maybe you should install some packet to build it.

sudo apt-get install build-essential
sudo apt-get install linux-headers-`uname -r`

For setting monitor mode

1. Fix problematic interference in monitor mode.

airmon-ng check kill

You may also uncheck the box "Automatically connect to this network when it is avaiable" in nm-connection-editor. This only works if you have a saved wifi connection.

2. Set interface down

sudo ip link set wlan0 down

3. Set monitor mode

sudo iw dev wlan0 set type monitor

4. Set interface up

sudo ip link set wlan0 up

For setting TX power (v4.3.21 branch only):

sudo iwconfig wlan0 txpower 30

or

sudo iw wlan0 set txpower fixed 3000

For Ubuntu 17.04 add the following lines

[device]
wifi.scan-rand-mac-address=no

at the end of file /etc/NetworkManager/NetworkManager.conf and restart NetworkManager with the command:

sudo service NetworkManager restart

astsam - for the main work + monitor/injection support - https://github.com/astsam

astsam     - https://github.com/astsam/rtl8812au
gnab       - https://github.com/gnab/rtl8812au
zebulon2   - https://github.com/zebulon2/rtl8812au
paspro     - https://github.com/paspro/rtl8812au
ulli-kroll - https://github.com/ulli-kroll/rtl8821au
tpircher   - https://github.com/tpircher/rtl8814AU