Help while installing

While installing Discourse using the official install I ran into a problem.

This is what I performed:

sudo -s
git clone /var/discourse
cd /var/discourse

This is the error I got:

sudo: unknown group: it
sudo: unable to initialize policy plugin

Any help would be appreciated!

I think it seems like a problem with your sudoers file. The error is telling that the group it is unknown. Check the configuration of the users that are allowed to perform sudo.