Not working on Virtue Premium Theme

Installed this plugin but nothing changed. I tested it with another theme and it works fine so I’m guessing it must be with something else. Here’s what I have in case it helps:
WC Version: 2.5.1
WP Version: 4.4.1
Parent Theme Name: Virtue – Premium
Parent Theme Version: 3.4.5
Parent Theme Author URL: http://www.kadencethemes.com

Does anyone know what in this themes related.php file I would need to edit to fix this?

https://wordpress.org/plugins/custom-related-products-for-woocommerce/