Ticket buyers do not automatically get a reminder about an upcoming event for which they have registered or purchased a ticket.
You can easily schedule a reminder for buyers &/or attendees using the email campaigns tool available via the top menu bar
You can even set up a series of reminder campaigns that go out at different timings that work for you, for example:
Campaign A is scheduled to send 1 week before the event
Campaign B is scheduled to send 1 day before the event
Campaign C is scheduled to send 1 hour before the event
