In order to use eBay store design templates(or any other store templates) you will have to be using eBay’s old store design. If you already updated to the new store look you can easily revert back to the original design.
Visit the following link: http://storefront.ebay.com/psn/edit
On Edit Store page there’s a Revert to my old Store button on the top right.
Once you click on the Revert to my old Store button a message will pop-up.
Click on the Revert my Store button and your store will updated to the classic design.
Now you can start using our store Store Designer solution.