Just an update: I went to Publix to buy the Lucky Charm bars and went down the cereal aisle. I grabbed the Lucky Charm box and checked out, but I didn't get them for FREE. What gives? I went to Customer Service and they explained I bought the wrong ones. Only the Soft Baked bars are Free with the digital coupon.
She offered to get one for me, so I waited. Turns out the Soft Bars were five aisles away from cereal, presumably with cookies. She refunded me the first box and I got the second one for FREE.
Just make sure you get the Soft Baked bars.