Wehn using Acymailing as action in Elementor forms, the user gets subscribed to the mailing list, but never gets a confirmation Email. When using the Elementor Widget for Acymailing, then this works, but with this widget you can not style it to our needs because lack of some basic styling options like SVG icons in Button.
With css its also not possible to do that, because you are using an input element with no label. Why don't you use a Button type=submit??
Or even better, make it possible to do a template override for this widget.