I have a Kindle, (not the Fire, but the one with free Wi-Fi and 3 G---it has a tiny keyboard across the bottom), and whenever I "buy" a free book, it just downloads into the Kindle. I get a "Thank you for you purchase" message, both on the Kindle, and in an email on my computer. I don't know what the Caliber program is. Maybe you have the Kindle Fire (?). I know someone with a Fire who has the "Prime" program. Hope someone else can help you. Maybe you can phone customer support.