18.04 Cannot install driver for D-Link DWA-172

I'm using Ubuntu 18.04 and I followed the instructions as described in D-Link DWA172 (ID 2001:3318) not working but upon execution of the "dkms-install" command, it cannot be found, any ideas why that may be? Quite new at this so please bare with me. Log from terminal as described below:

crisp@pc:~$ lsusb
Bus 002 Device 002: ID 8087:8000 Intel Corp. 
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 002: ID 8087:8008 Intel Corp. 
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 002: ID 8086:0b3a Intel Corp. 
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 004: ID 2001:3318 D-Link Corp. 
Bus 003 Device 002: ID 045e:07b2 Microsoft Corp. 
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

crisp@pc:~$ git clone https://github.com/aircrack-ng/rtl8812au.git
Cloning into 'rtl8812au'...
remote: Enumerating objects: 16, done.
remote: Counting objects: 100% (16/16), done.
remote: Compressing objects: 100% (16/16), done.
remote: Total 10540 (delta 7), reused 3 (delta 0), pack-reused 10524
Receiving objects: 100% (10540/10540), 70.21 MiB | 631.00 KiB/s, done.
Resolving deltas: 100% (7333/7333), done.
crisp@pc:~$ cd rtl8812au
crisp@pc:~/rtl8812au$ sudo ./dkms-install.sh
[sudo] password for crisp: 
sudo: ./dkms-install.sh: command not found