First things first, clone Tuleap sources.
$ git clone https://tuleap.net/plugins/git/tuleap/tuleap/stable.git tuleap
The folder you are cloning into must be named tuleap
.
In order to ease the setup, we are using an anonymous clone url. If you already have credentials on our gerrit server you can fetch the tuleap project. In any case, we will configure the gerrit server as a git remote later.