Google Calendar
Google Calendar is a Google-supported calendar service where you can create events for meetings, appointments, and important days and receive notifications when that day comes. You can invite someone else to the event you started with Google Calendar, or you can receive notifications by SMS or e-mail when the event is due.
forms.app and Google Calendar integration give you great options. You can create an event entry in Google Calendar with the information you collect from your event forms in forms.app and then add an attendee to the event for each record you receive.