Click element would be used for object. In this case I can suggest you to use Click ID or Click Classes instead and match it with parameters from your button.
example: Click ID - matches - product-addtocart-button
If you aren’t sure what variables are visible for object you are clicking, there is also another method. You can always open debug mode → connect to tested website → go to “Events” instead of tags → select from list action you just did → check variables visible by tag manager
Class is changing when element is clicked and I think it’s gone for brief second - but I’ve noticed in console that there is stg.formSubmit with each Add to cart button pressed.
Maybe you can do Form submission trigger instead and set Form URL to starts with → "https://www.matthys.net/en/checkout/cart/add/ ?