Use library without namespace

Hi , i want use this php library :

https://github.com/s2software/fatturapa

if i add namespace to FatturaPa.php (renamed ) i have this error :
Class 'App\ThirdParty\Fatturapa\DOMDocument' not found
this is the error row :
471        $doc = new DOMDocument();
if i load with require_once: require_once (APPPATH.'/ThirdParty/Fatturapa/FatturaPA.php');
folder three:
https://imgur.com/KLiuofM.png
i have thi error :
Class 'App\Controllers\FatturaPA' not found

how can i use the library ?
471         $doc = new DO
471        $doc = new DOMDocument();MDocument();
Class 'App\ThirdParty\Fatturapa\DOMDocument' not found Class 'App\ThirdParty\Fatturapa\DOMDocument' not found 

Without adding the namespaces.
Or adding the correct namespaces in all files.

It seems you need to learn PHP's namespaces and PSR-4 autoloader.

ci-phpunit-test | CodeIgniter Testing Guide | CodeIgniter 3 to 4 Upgrade Helper

app/Config/Autoload.php
classmap property

Don't force the namespace in someone else's library.

Without adding the namespaces.
Or adding the correct namespaces in all files.

It seems you need to learn PHP's namespaces and PSR-4 autoloader.

There is only one file DOMDocument is a PHP function

PHP internal class is located in global namespace.
See https://www.php.net/manual/en/language.n...llback.php

ci-phpunit-test | CodeIgniter Testing Guide | CodeIgniter 3 to 4 Upgrade Helper

app/Config/Autoload.php
classmap property

Don't force the namespace in someone else's library.

Removed namespace . 
In config Autoload :

Code:

public $classmap = [


'FatturaPA' => APPPATH.'/ThirdParty/Fatturapa/FatturaPA.php',

];

same error : https://imgur.com/Xux8b27.png

This is my folder three : https://imgur.com/Y886AbM.png

use FatturaPA;