How do I install Let's Encrypt certificate in a shared hosting Godaddy server??

I'm following the tutorial https://fr.godaddy.com/help/install-a-lets-encrypt-ssl-apache-20245, but when I typed the command ./letsencrypt-auto --help I got the error : "sudo" is not available, will use "su" for installation steps... Sorry, I don't know how to bootstrap Certbot on your operating system! You will need to bootstrap, configure virtualenv, and run pip install manually. Please see https://letsencrypt.readthedocs.org/en/latest/contributing.html#prerequisites for more info.
P.S: which su or which sudo doesn't give any output, and $ cat /proc/version gives: Linux version 2.6.32-673.8.1.lve1.4.3.el6.x86_64 ([email protected]) (gcc version 4.4.7 20120313 (Red Hat 4.4.7-16) (GCC) ) #1 SMP Wed Feb 10 08:57:30 EST 2016

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