What this article doesn't address is the systemic download failure rate part of the process. Many users experienced issues with getting their codes. The beta page went down because of problems and that is understandable. However, Apple rolled Mavericks out through the Mac App Store as well as countless updates to the OS and all the 3rd party apps they sell. Mavericks didn't have the download bugs that this "limited" beta has and continues to have.
Apple has no issue selling movies from the iTunes Store, some of which are 7-12GB in size. And yet many many users reported that when they try to download this 5GB Yosemite build that it simply fails time after time, getting anywhere from .5 to 4.5GB complete, often restarting itself at 0MB and then beginning the process again, only to ultimately fail.
"An error has occurred"
"Try your purchase tab again"
This happens over and over for some users but not for others. You can't begin where you left off, and internet speed is not a factor. Doesn't matter if you reboot, empty trash, clear caches. There is no apparent fix. And of course no actual help from Apple.
Sorry Apple, we realize this is a public beta, but this part of the process should be fairly simply and straightforward.
FAIL is the message we get over and over. Fail is what it is then.
You should contact Apple right away and request a refund for what you paid for the beta!