Why can't my customers use Apple pay to pay for their subscription order?

Apple pay is currently only available for merchants who's stores are based in either: United States, Canada, Australia, and New Zealand.
If your store is based outside of these locations, it unfortunately isn't going to be available.

Learn more about this directly from Shopify below:https://help.shopify.com/en/manual/products/purchase-options/subscriptions/shopify-subscriptions/considerations