I have also received this and would appreciate your help as the deadline is fast approaching.

Error! It looks like we've temporarily run out of gift codes for Minecraft for Windows 10. Don't worry though, more codes should be on their way. Please check back later!

This message pops up every time that I attempt to get my free copy of Windows 10 edition, as I purchased java in 2014. I have looked through many forums for a fix, and the only thing I could find was that I needed to report a bug directly to get support. Thank you for your help, if there is no way to fix this I completely understand.