PDF Product Vouchers for WooCommerce

I allow multiple pdf template to choose from when ordering a gift card on my website. But when people want to add the gift card to cart without choosing their preferred template, the add to cart button does not work and they don’t get any error message indicating what they missed. I’d like to be able to pre-select the first template by default, so they can either choose the one they prefer if they saw it, or have the default one without having a cart error resulting often in cart abandon.