If you actually need rtl8812au driver then it’s to be found in official ubuntu repositories : https://packages.ubuntu.com/search?keywords=rtl8812au-dkms&searchon=names
…so Jason’s piece of advice sounds fair : get a wired connection, and install it.
If « the app-store » does not help ( can one install driver with it ? ) then it’s only that one short command :
sudo apt install rtl8812au-dkms
that may help.
Problem here : you probably tried to compile the driver from sources, I hope this past attempt will not interfere with that later regular installation.
( some examples video : https://www.youtube.com/results?search_query=ubuntu+18.04+rtl8812au-dkms )