But it didn't fail to download. It downloaded completely and then failed to install.
I'm trying to deploy OS X Server to a few machines and I have tried assigning it to both a user and a specific machine. In both cases I ran into this same issue. I get no error message or error code other than "failed to download".
I am quite confident the user-based licensing is working because the app displays in my "Purchased" tab in the App Store, but beside the download button it says "An error has occurred" and the download button is completely grayed out. I can still try to re-download/install OS X Server via the Self Service portal but I just run into the exact same problem.
[Edit]
I will add that the OS X Server app is still hanging in my Applications folder with the download bar still displayed (but completed, only remaining bar is the installation portion) and will not let me cancel the download.