Configuration file not loaded

I am trying to setup this CodeIgniter Multilevel Menu library but I can't get it to work. Take a look to my `autoload.php` file:

PHP Code:

$autoload['libraries'] = ['database', 'ion_auth', 'form_validation', 'Multi_Menu'];
$autoload['helper'] = ['url', 'language'];
$autoload['config'] = ['multi_menu']; 


If I am not wrong both the library and the config should be autoloaded but they are not and I don't know why. Every time I try to load the page I got this error:

A PHP Error was encountered
Severity: 4096
Message: Argument 1 passed to Multi_Menu::render() must be of the type array, none given, called in /var/www/html/plataforma56.local/application/controllers/Welcome.php on line 15 and defined
Filename: libraries/Multi_Menu.php
Line Number: 286
Backtrace:
File: /var/www/html/plataforma56.local/application/libraries/Multi_Menu.php
Line: 286
Function: _error_handler
File: /var/www/html/plataforma56.local/application/controllers/Welcome.php
Line: 15
Function: render
File: /var/www/html/plataforma56.local/index.php
Line: 288
Function: require_once

What I am missing here? How do I know if a config file has been loaded?

Thanks in advance