5 project and after install Laravel and make `php artisan serve` it fails.

> 
> PHP Warning: require(/var/www/html/sidbrint/vendor/autoload.php):
>  failed to open stream: No such file or directory in
>  /var/www/html/sidbrint/artisan on line 18
> 
> 
> PHP Fatal error: require():
>  Failed opening required '/var/www/html/sidbrint/vendor/autoload.php
>  (include\_path='.:/usr/share/php') in /var/www/html/sidbrint/artisan on
>  line 18
> 
> 
> 

I'm using an Ubuntu Server and I don't know hat to do.

---

When I install Laravel I use `composer create-project --prefer-dist laravel/laravel blog "5.5.*"`

If I don't put the version, it installs the 5.4 version, that works fine, but I need version 5.5 because is LTS.