Hello! I have a MacBook Pro Mid 2014 with OS X 10.10.4 installed and recently was going to update to OS X 10.11 but when I press download developer beta it does launch the app store but it doesnt get me to any page. I tried to manually enter the code, but when I do that it says "Your code could not be redeemed at this time!"
https://forums.developer.apple.com/message/5958#5958
Found the solution here!