Tap the portrait icon in the top right corner of the lists manager: 

Select "Create an account":

Fill out "Email", "Login" and "PIN" fields and tap "Done":

All these fields are required. Note that your login and email should be unique, i.e. you cannot use the same login or email for several accounts. Besides, you are offered a random 4-digits PIN – you can leave it as is or change it to your own 4 digits.