Recent PHPBB 3.1 Posts Code Make it work with WP 4.31

I am trying to make this code work with WordPress 4.31 so it will display PHPBB 3.1 Recent posts on the sidebar or in frontpage, but when I implemented it everything is blank and it’s not executed.

<?php
/*
* news2.php
* First post of latest topic in forum 28
*/

define('IN_PHPBB', true);
$phpbb_root_path = (defined('PHPBB_ROOT_PATH')) ? PHPBB_ROOT_PATH : './forums/';
$phpEx = substr(strrchr(__FILE__, '.'), 1);
include($phpbb_root_path . 'common.' . $phpEx);
include($phpbb_root_path . 'includes/bbcode.' . $phpEx);
include($phpbb_root_path . 'includes/functions_display.' . $phpEx);

// Start session management
$user->session_begin();
$auth->acl($user->data);
$user->setup('viewforum');

/* create_where_clauses( int[] gen_id, String type )
* This function outputs an SQL WHERE statement for use when grabbing
* posts and topics */

function create_where_clauses($gen_id, $type)
{
global $db, $auth;

    $size_gen_id = sizeof($gen_id);

        switch($type)
        {
            case 'forum':
                $type = 'forum_id';
                break;
            case 'topic':
                $type = 'topic_id';
                break;
            default:
                trigger_error('No type defined');
        }

    // Set $out_where to nothing, this will be used of the gen_id
    // size is empty, in other words "grab from anywhere" with
    // no restrictions
    $out_where = '';

    if( $size_gen_id > 0 )
    {
    // Get a list of all forums the user has permissions to read
    $auth_f_read = array_keys($auth->acl_getf('f_read', true));

        if( $type == 'topic_id' )
        {
            $sql     = 'SELECT topic_id FROM ' . TOPICS_TABLE . '
                        WHERE ' .  $db->sql_in_set('topic_id', $gen_id) . '
                        AND ' .  $db->sql_in_set('forum_id', $auth_f_read);

            $result     = $db->sql_query($sql);

                while( $row = $db->sql_fetchrow($result) )
                {
                        // Create an array with all acceptable topic ids
                        $topic_id_list[] = $row['topic_id'];
                }

            unset($gen_id);

            $gen_id = $topic_id_list;
            $size_gen_id = sizeof($gen_id);
        }

    $j = 0;    

        for( $i = 0; $i < $size_gen_id; $i++ )
        {
        $id_check = (int) $gen_id[$i];

            // If the type is topic, all checks have been made and the query can start to be built
            if( $type == 'topic_id' )
            {
                $out_where .= ($j == 0) ? 'WHERE ' . $type . ' = ' . $id_check . ' ' : 'OR ' . $type . ' = ' . $id_check . ' ';
            }

            // If the type is forum, do the check to make sure the user has read permissions
            else if( $type == 'forum_id' && $auth->acl_get('f_read', $id_check) )
            {
                $out_where .= ($j == 0) ? 'WHERE ' . $type . ' = ' . $id_check . ' ' : 'OR ' . $type . ' = ' . $id_check . ' ';
            }    

        $j++;
        }
    }

    if( $out_where == '' && $size_gen_id > 0 )
    {
        trigger_error('A list of topics/forums has not been created');
    }

    return $out_where;
}
$search_limit = 5;

    $forum_id = array(2, 5);
    $forum_id_where = create_where_clauses($forum_id, 'forum');

    $topic_id = array(20, 50);
    $topic_id_where = create_where_clauses($topic_id, 'topic');

$posts_ary = array(
        'SELECT'    => 'p.*, t.*, u.username, u.user_colour',

        'FROM'      => array(
            POSTS_TABLE     => 'p',
        ),

        'LEFT_JOIN' => array(
            array(
                'FROM'  => array(USERS_TABLE => 'u'),
                'ON'    => 'u.user_id = p.poster_id'
            ),
            array(
                'FROM'  => array(TOPICS_TABLE => 't'),
                'ON'    => 'p.topic_id = t.topic_id'
            ),
        ),

        'WHERE'     => $db->sql_in_set('t.forum_id', array_keys($auth->acl_getf('f_read', true))) . '
                        AND t.topic_status <> ' . ITEM_MOVED . '
                         AND t.topic_visibility = 1',

        'ORDER_BY'  => 'p.post_id DESC',
    );

    $posts = $db->sql_build_query('SELECT', $posts_ary);

   $posts_result = $db->sql_query_limit($posts, $search_limit);

      while( $posts_row = $db->sql_fetchrow($posts_result) )
      {
         $topic_title       = $posts_row['topic_title'];
         $post_author       = get_username_string('full', $posts_row['poster_id'], $posts_row['username'], $posts_row['user_colour']);
         $post_date          = $user->format_date($posts_row['post_time']);
         $post_link       = append_sid( 'https://www.imfiles.com/forums/viewtopic.php?t=' . $posts_row['topic_id'] . '&p=' . $posts_row['post_id']) . '#p' . $posts_row['post_id'];

         $post_text = nl2br($posts_row['post_text']);

         $bbcode = new bbcode(base64_encode($bbcode_bitfield));
         $bbcode->bbcode_second_pass($post_text, $posts_row['bbcode_uid'], $posts_row['bbcode_bitfield']);

         $post_text = smiley_text($post_text);

         $template->assign_block_vars('announcements', array(
         'TOPIC_TITLE'       => censor_text($topic_title),
         'POST_AUTHOR'       => $post_author,
         'POST_DATE'       => $post_date,
         'POST_LINK'       => $post_link,
         'POST_TEXT'         => censor_text($post_text),
         ));
      }

page_header('External page');

    $template->set_filenames(array(
        'body' => 'news.html'
    ));

    page_footer();
 ?>

it works on it’s own, like here the outcome of my page
https://www.imfiles.com/news.php
But when I put it anywhere in the wordpress template everything after the code goes blank and there is no output.