This way clients/employees are notified, confirmed and reminded when booking an appointment.
Go to Settings > Bookings > Notifications from the main menu.

"Client" tab
Notice of meeting
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Appointment Details - Notifications will be sent when an appointment is booked.
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Confirmation Request - Automatically send a notification to clients asking them to confirm that they will come to the meeting.
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Appointment Reminders - Automatically send notifications reminding your clients about their appointment.
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Reschedule an appointment - Notifications will be sent when an appointment is edited.
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Cancel meeting - Notifications will be sent when the meeting is deleted.
"Employee" tab
Notice of meeting
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Appointment Details - Notifications will be sent when an appointment is booked.
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Reschedule an appointment - Notifications will be sent when an appointment is edited.
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Cancel meeting - Notifications will be sent when the meeting is deleted.
Notifications will be sent according to the selected tariff plan
At the end, be sure to click the "Save changes" button.