Redemption code for Lightroom 6

I recently purchased Lightroom 6 from Best Buy as a disk. There is no serial number with the disk and the serial number on the receipt contains letters, so it won't work. I loaded it into my computer and followed the address to type in my redemption code to receive my serial number and it said that the serial number was not necessary. I finished loading it onto my computer but it turns out to be a trial offer and was trying to get me to purchase the subscription. I uninstalled it and tried again with the same result. Now it won't accept my redemption code. I have a $160 disk that won't load and I can't return.