Hi @matthewpmunger – That error is because SSL is required to use any of the Ecommerce functionality on live sites (for store security purposes).
We’re working on improving the experience and messaging around this to make it easier to avoid (i.e. automatically use SSL for webflow.io subdomain sites), and more clear when you’re testing in a case like this.
But for now, you can either set your custom domain to SSL and it will work fine, or if using your webflow.io subdomain can just go to the https url and you will be all-good: https://ecommerce-test-c1a366.webflow.io/product/un-american-pie