If you are using a Samsung device such as a Galaxy S or Note series, and having trouble downloading assets or connecting to the game, there is a possible reason why. Samsung devices have a "download booster" which basically means the device is running both Wi-Fi and your cellular network at the same time to ensure that a connection is made. This can actually interfere with connecting to the game. Try turning off the download booster from your device settings and this should help you to connect to the game.