Students don't need to log in to Kodable to participate in the Hour of Code! Just head to https://game.kodable.com/hour-of-code and select "Play Without Saving".
If you have a Kodable account and your students already have profiles, their Hour of Code progress will save. Students can log in on their iPads or on the web at kodable.com/login using the "School Profile" option, entering their class code, and selecting "Playing at School".
View more details about how to prepare your devices here.