There was an error server side, should be fixed now (or in the next hour tops).
Yes, I can confirm this. Should be ok soon.
Hmm, apparently not :p I just did some testing amid reports of problems and there still seems to be issues. I have also installed the GOG Downloader on one of my other systems to help test.
Alan Wake either gets stuck on "Preparing..." or the downloader crashes. At one point I managed to get it to start downloading on this system but the size reported was incorrect (~5GB). Now it just crashes every time on this system while it gets stuck most of the time on the other system.
This problem seems to be limited to Alan Wake as all other games I've tried have downloaded on both systems without any problems.