XF 2.0 vBSEO redirect not working

[Ivancas]

I have the following rules set in .htaccess:

RewriteRule ^attachments/(.+)/([0-9]+)[d-](.+)$ attachment.php?attachmentid=$2 [R=301,L]
RewriteRule ^attachments/[a-zA-Z0-9_\-]+/([\d]+)-[a-zA-Z0-9_\-]+\.[a-zA-Z\-]+$ attachment.php?attachmentid=$1 [R=301,L]

However, when vBSEO attachment URL is visited, it redirects to
http://www.domain.com/home/user/public_html/forums/install/index.php

I'm SO confused why it redirects to install/index.php.
I'm currently using vb4 redirect script: https://xenforo.com/community/resources/vbulletin-4-x-url-redirection.120/

<?php

/* ----------------------------------------------------------- *\
This variable defines where XenForo is installed.

If you have not installed XenForo into the same directory in which
vBulletin was installed, you will need to provide the full path to
the XenForo directory here. Remove the leading // and then enter
the path as in the following examples:

    $fileDir = '/home/example/public_html/new_forums';

    $fileDir = 'C:/inetpub/wwwroot/xenforo';

\* ----------------------------------------------------------- */

    $fileDir = '/home/user/public_html/community';

/* ----------------------------------------------------------- *\
This constant defines the table from which the import redirection
scripts will fetch their data. Normally they will use the table
'xf_import_log', but if you have archived your import data, you
should provide the name of the archive table here. Remove the
leading // and then replace 'import_log_x' with the name of your
archive table, as in the following examples:

    define('IMPORT_LOG_TABLE', 'my_import_log');

    define('IMPORT_LOG_TABLE', 'import_log_my_forums');

\* ----------------------------------------------------------- */

    define('IMPORT_LOG_TABLE', 'archived_import_log');

Any idea?