You must be signed into your account before checking out for the points to be redeemable. Here is a quick video that walks through the sign in and checkout process.
I cannot apply my rewards at checkout. How do I access my rewards on your site?
By Anna Wolff
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Why can’t I apply my points on my order?
Points can only be redeemed on full priced items. This means that if there is a sale product or promo code being applied on the order, you will not be able to also use your points towards that order.