// Registration will extra fields: first name, last name phone number.
// The redirect, extra fields and requried fields are optional.
// Without those, it will only show email and password fields.

[firebase_register required_fields='firstName,lastName,phoneNumber' extra_fields='firstName,lastName,phoneNumber' redirect='/']

If you want to send a verification email after user registers, you can add this option: send_email_confirmation=true
Remember that if user doesn't verify their email, they won't be allowed to login next time.