This depends on where you are running this from. like for "foo"
root@EPUMBI:~# git clone https://github.com/epumbi/hacking.git
Just to know where you are from the place you are initiating the command type the following;
root@EPUMBI:~# pwd
/root
So from the above after typing pwd which is print working directory, it tells you that you are on the root directory.
Then to see your files downloaded like the above, you can use ls to view the files on the root directory/folder, then type the following to get into the directory so that you can execute the program.
root@EPUMBI:~# cd hacking
Don't forget to change the permissions to allow the file to be executable by doing the following command;
root@EPUMBI:~# chmod +x ./install.sh
I Am running the cmd in root mode so you can use sudo chmod +x ./install.sh
Hope it helps!