It appears Apple Pay may not be live on the Stripe end although enabled on the Shopify side. This can be resolved by getting in direct contact with Stripe. I have linked their support channel below:
Don’t forget that you can eliminate your transaction fees with us by adding Shopify Payments as a gateway (if supported in your country) option for your customers as well. With Shopify Payments, it’s as simple as ticking a box in the payment gateway, with no URL required. You can find the rest of the instructions in this guide.
My suggestion would be to get in contact with Stripe as they will be able to provide some additional information regarding this. Your domain provider may be able to assist you as well.