Your Storefront link will not work if you have not yet published your products on your Storefront.

To publish your products and create your Storefront, you will need to select the products you want to publish in “My Products” and click on "Publish to my Storefront" on the menu on the right.

Confirm you accept the terms and conditions with the pop-up that will open.

You will then see your products in “My Storefront”. You can double-check they have been published by looking if there's a little boutique icon at the top-right of the pictures.

You can find more information in this video.