We included Booked premium plugin to let you easily manage your appointments. You can also find detailed instructions and tips from official plugin documentation here.
When you installed the plugin. You can find its setting page in WordPress Dashboard > Appointments.
To add booking calendar form to your page. You can simply use this shortcode to page content.
It will display calendar booking form like above image.
So when you want to make an appointment, click on available date and it will open each available time of selected date.
Click “Book Appointment” will open popup and then complete the booking form. The appointment will be sent to your WordPress Dashboard > Appointments > Pending