Installing laravel on existing project
Go to your www folder
cd /var/www
Git clone your application (not that here the directory must not exist):
git clone https://github.com/antonioribeiro/application
CD into the folder
cd application
Execute composer update (if you are in a development environment)
composer update
Or execute composer install (if you are in a production environment)
composer install
Note that for composer install or composer update, the folder may actually have files and even a vendor folder created, there is not such obstacle.