New extension, does not work!

[userform3]

Hi,

In forum, vbulletin version 5.2.5, I would like to create a new extension.

To the facts, the forum is only accessible to registered users, if a user is not registered, he can see the forum, not.
If the user is registered, his real first name and last name should be displayed.
These data are located in a separate table in the forum database and must be read out additionally.

To implement this, we introduced a new product in the area "Products & Hooks" in "Manage Products" with the name "klarnamenIntern".
A new add-on was created in "Manage Hooks". To test with "klarnamen".
In the directory .../forum5/core/packages/klarnamenIntern the following directories with files were created:

klarnamenIntern/api/site.php
klarnamenIntern/xml/product_klarname.xml
product.php

Unfortunately, I can not access the forum data via the procedure described above.
That is, About the file klarnamenIntern/api/site.php I can not read posts from the forum.

What is the error or the causes why I can not access the data?
How can I access the PHP files klarnamenIntern/api/site.php from the forum or connect?

Example the file klarnamenIntern/api/site.php

PHP Code:

<?php if(!defined('VB_ENTRY')) die('Access denied.');

class Interred_Api_Site extends vB_Api_Extensions 
{
    protected $product = 'klarnamenIntern';
    protected $developer = 'die-user';
    protected $title = 'Global';
    protected $minver = '5.2.0';    
    protected $AutoInstall = 2;
    protected $extensionOrder = 10;
    
    function __construct () {
        $this->fetchThreads();
        
        // Only the default data is taken from the forum
        $forum = $this->do_get_forum();
        echo "<pre>forum:: " .print_r( $forum, true ). "</pre><hr>";        
    }
    
    public static function fetchThreads(){ 
        // Only user data, which is calling the forum!
        $userinfo = vB_Api::instance('user')->fetchUserInfo();
    }
    
    // ##########################################
    // From here, methods taken from another extension.
    
    public static function do_get_forum_data()
    {
        $cleaned = vB::getCleaner()->cleanArray($_REQUEST, array(
            'forumids' => vB_Cleaner::TYPE_STR,
        ));

        if (!isset($cleaned['forumids']) || strlen($cleaned['forumids']) == 0) {
            return array('forums' => array());
        }

        $forumids = explode(',', $cleaned['forumids']);

        $forum_data = array();

        foreach ($forumids AS $forumid) {
            $forum = self::fr_get_and_parse_forum($forumid);
            if($forum != null) {
                $forum_data[] = $forum;
            }
        }

        if(!empty($forum_data)) {
            return array('forums' => $forum_data);
        } else {
            return null;
        }
    }
    
    function fr_get_and_parse_forum($forumid, $foruminfo = false)
    {
        $userinfo = vB_Api::instance('user')->fetchUserInfo();
        $options = vB::get_datastore()->get_value('options');

        if(!$foruminfo) {
            $foruminfo = vB_Api::instance('node')->getFullContentforNodes(array($forumid));
            if (empty($foruminfo)) {
                return null;
            }
            $foruminfo = $foruminfo[0];
        }
        if(!$foruminfo) {
            return null;
        }

        $type = 'old';

        if ($options['threadmarking'] AND $userinfo['userid']) {
            $userlastvisit = (!empty($foruminfo['readtime']) ? $foruminfo['readtime'] : (vB::getRequest()->getTimeNow() - ($options['markinglimit'] * 86400)));
        } else {
            $lastvisit = vB5_Cookie::get('lastvisit', vB5_Cookie::TYPE_UINT);
            $forumview = fr_fetch_bbarray_cookie('channel_view', $foruminfo['nodeid']);

            //use which one produces the highest value, most likely cookie
            $userlastvisit = ($forumview > $lastvisit ? $forumview : $lastvisit);
        }

        if ($foruminfo['lastcontent'] AND $userlastvisit < $foruminfo['lastcontent']) {
            $type = 'new';
        } else {
            $type = 'old';
        }

        $out = array(
            'id' => $foruminfo['nodeid'],
            'new' => $type == 'new' ? true : false,
            'name' => html_entity_decode(strip_tags($foruminfo['title'])),
            'password' => false, // No forum passwords in vB5
        );

        $icon = self::fr_get_forum_icon($foruminfo['nodeid'], $foruminfo == 'new');
        if ($icon) {
            $out['icon'] = $icon;
        }

        if ($foruminfo['description'] != '') {
            $desc = strip_tags($foruminfo['description']);
            if (strlen($desc) > 0) {
                $out['desc'] = $desc;
            }
        }
        return $out;
    }
    
    function fr_get_forum_icon ($forumid, $shownew, $showlink=false)
    {
        $basedir = MCWD . '/icons/';

        $new = $old = $link = null;

        if (@file_exists($basedir . 'forum-default-new.png')) {
        $new = 'forum-default-new.png';
        if (@file_exists($basedir . 'forum-default-old.png')) {
            $old = 'forum-default-old.png';
        } else {
            $old = $new;
        }
        }
        if (@file_exists($basedir . 'forum-default-link.png')) {
        $link = 'forum-default-link.png';
        }

        if (@file_exists($basedir . 'forum-' . $forumid . '-new.png')) {
        $new = 'forum-' . $forumid . '-new.png';
        if (@file_exists($basedir . 'forum-' . $forumid . '-old.png')) {
            $old = 'forum-' . $forumid . '-old.png';
        } else {
            $old = $new;
        }
        }
        if (@file_exists($basedir . 'forum-' . $forumid . '-link.png')) {
        $link = 'forum-' . $forumid . '-link.png';
        }

        return ($showlink ? $link : ($shownew ? $new : $old));
    }
}
?>

greetings