Thank you very much for choosing our theme and for contacting us.
Woocommerce does not provide the option by default. You will need to find a plugin for the purpose. We have not tested any with the theme that is why we can hardly recommend any. Try free plugins first of all or paid that guarantee 14/30 days refund.
You can add the button in the area After add to cart button in the Theme Settings > Product page, this button would be one and the same for all the products and would be under the Add to cart button.