Moodle itself does not support automatic reminders. There is a plugin for this:People can register there. Of course they can also register directly on Moodle (and then self-enroll to the course).However the advantage of Indico is that it can send reminders before a meeting. I am not sure whether Moodle is able to send reminders.
https://moodle.org/plugins/mod_booking
Regards,
Mitja