Track Form submit with MC4WP Plugin

I’m using the MC4WP plugin on my Wordpress page. I’d like to add a goal when the user submits the newsletter form. According to a past thread from 2017 (Is Form Analytics required to track form submissions?) I should add something to the form (class) and an additional event listener. I’m not sure where to add it.
The form edit field looks like this:

Where to add the class part?

I assume I have to add the event listener below the standard tracking code in Wordpress/Matomo Plugin?

Thanks for any help! :slight_smile: