I have tried off an on for the past 3 or so hours to redeem my free windows 10 edition of Minecraft. I have owned the java edition of the game for several years (Since 2012) and I just now heard that you were able to redeem the free Windows 10 version as well, but when I went to the Mojang site and tried redeeming it, it said that no copies are currently available and it also told me to check back later, which I did periodically for the next 3 hours about every half hour or so, with no results.