compatibility with Woocommerce email template customizer

I am trying to customize the emails i created with this plugin by using the ‘WooCommerce email template customizer’. In this link they say that their plugin is compatible with yours: https://villatheme.com/knowledge-base/compatibility-scenarios-with-3rd-party-email-plugins/

I am not able to connect the two plugins in the way that is described in step 3. At the end of the article it says that the code needs to be implemented by the author of the plugin. is this something you can solve? or can you tell me what i am doing wrong?