Critical error with metabox (not AIO)

Hi there,

I went through the existing threads but could not find a quick fix to my issue.
I have the Appsumo tier 1 - so not AIO

Whenever I activate metabox plugin + an extension, my product page throws a critical error.

I tried navigating to /plugins/meta-box/inc/helpers/array.php to apply this fix, but I don't think I have the same file.

Here is what I have in my file:

<?php
use MetaBox\Support\Arr;

/**
 * No longer needed. Keep it here for backward compatibility.
 */
class RWMB_Helpers_Array extends Arr {}

Let me know if you need more information.