Registration is not required. If you are a schedule manager, you will need to register to setup your schedule. Once the schedule is setup and ready, invite users via the Users menu. This will create the user's account and send an automated invite which includes the user name and a temporary password. If you are not a schedule manager, no need to register. Just wait till you receive your email invite.
Contact firstname.lastname@example.org for assistance creating your Schedule.Work custom schedule.