Unable to deploy project to server

I've been trying to install Laravel 5 on Forge by following this tutorial (https://laracasts.com/series/server-management-with-forge/episodes/3) but I get an error.

We were unable to deploy your project to your server

Warning: Permanently added the RSA host key for IP address '[...]' to the list of known hosts.
From github.com:[...]/laravel
 * branch            master     -> FETCH_HEAD
Already up-to-date.
Loading composer repositories with package information
Installing dependencies from lock file
Nothing to install or update
Generating autoload files
Generating optimized class loader
Compiling common classes


                                                                                          
  [PDOException]                                                                          
  SQLSTATE[HY000] [1045] Access denied for user 'forge'@'localhost' (using password: NO)

I followed the videos instructions of installing the server and linking the Git repository from where I've forked this (https://github.com/laravel/laravel). The video uses this repo (https://github.com/laracasts/Forge-Demo) but it seems to me that it's Laravel 4, and I'd want L5.

I completely dropped and reinstalled the server, but I have the same issues. Is there something I need to do that's not shown in the video?

Sorry, I'm a complete newbie here.