Hey I took a look at your page and noticed that your body classes show product-template-default which means WooCommerce is not recognising any custom product template override so its hooks including the Add to Cart button are never firing.
This usually happens when the template is built as a regular Elementor page instead of a Theme Builder Single Product template. A regular Elementor page does not trigger WooCommerce hooks which is why the button never shows up.
To fix this open your Single Product template in Theme Builder and check if the Add to Cart widget is placed inside it. If the template is not in Theme Builder at all you would need to create a new one under Templates -> Theme Builder -> Single Product and set the display condition to Singular -> Product. Then make sure you are using the WooCommerce Add to Cart widget specifically and not a generic button widget.
Hope that helps.
