Does Shipping Rates Calculator+ work on my Facebook or Buy Button sales channels?

Unfortunately, our apps only work on the Online Store sales channel.

While the Shopify platform offers different sales channels (see https://apps.shopify.com/categories/sales-channels), it does not provide a way to run apps on most sales channels.

If you have any third-party app running on a Facebook channel, for example, it probably is not a native Shopify app but an integration with a standard web application.