It is saying that there is a google double click error when I try to join a tournament that has the second confirmation to join.
System, operating system, and browser:
iPhone with iOS 8 using Safari.
It allowed me to join when I used my computer with IE but not my phone. Tested it today with the Great War tournament that allows free players and it came up with the error I also had it happen to the 1 vs 1 bot tournament that I joined before I switched to my computer in order to participate in the tournament. From what I can tell it is only the auto tournaments.