Within your booking module settings, you can edit the information given to your users when they make a booking.
Select the 'Bookings' module from the list of options on the left, within the admin area.
Click on the 'Settings' button on the top right.
Once in booking settings select 'Edit booking confirmation'.
Here you can describe what your users should do when they turn up to your venue or any other information that may be relevant to their booking such as a PIN.
Make sure you save any changes you make using the 'Save' button at the bottom of the page before you exit.