Woolementor has a Thank You widget included. You just need to drag the widget to your page using the Elementor editor.
Please note, unless you have a separate page set as the Thank You page (with some plugin or custom code), you need to add this widget to the Checkout page (the page that holds the Billing Address, Shipping Address, etc widgets). But, you need to use a separate section for this.
Also, it’s recommended that you’ll use a full-width section that holds the Thank You widget only.