Hi!
Don’t use the github version and follow the instructions as in the course instead. To be able to install veil follow these steps:
– Import a fresh custom kali
– Run the command leafpad /etc/apt/sources.list
– Comment the line about kali-rolling repository, so it should looks like:
#deb http://http.kali.org/kali kali-rolling main contrib non-free
– Run the veil installation script again

Greetings!
Diego