Solution 1: If you're unable to log into the game when you have downloaded it, it is because you must click on the 'Play Game' button on this website, and keep that window open in order for your account to connect to the server and log you in (it can take up to 60 seconds, give it some time).
Solution 2: If you're having trouble opening up the game, please make sure that your firewall isn't blocking it somehow.
Solution 3: Make sure you've gone through the setup process so everything can be put correctly in place in order for you to be able to open up the game and such.