You have several options for creating accounts in the Cocoon cloud.
Username and password
Classic one. Just fill the signup form and provide a valid email address an a password. you will be able to change your password later from your profile configuration.
You signup using your google account. The Google account dialog will show asking you for your Google email and password.
You signup also with a Github account. Same as the Google one, this will show the Github authentication dialog where you will need to provide your Github username and password and you will be automatically signed up.