add to cart event

Hello,

Please check at this product page at https://tao.ooo/painting/birds-painting/

I am trying to setup a “Add to cart” event trigger, and here is wha I did:

https://prnt.sc/u4yAXP67cpf0

so, nm-simple-add-to-cart-button single_add_to_cart_button is the class name?

I add that code into Custom Class field, here is the screnshot https://prnt.sc/xRWyQ2eFYL5s

but it does not trigger popup, what did I missed please?