In order for the code to apply, you need to first confirm your delivery address. We advise progressing through the checkout process, as you will have another chance to enter your code at the 'review and pay' stage. Just click 'Add Discount Code' before entering your payment details.
As long as the order qualifies, and the standard shipping option is selected on the shipping options page, the code will apply free shipping for you.
If you're still having issues with the code after reaching the 'Pay and review' stage, please reach out to our customer service team who will assist.