If guests do not come to the meeting place at the meeting time on the trip day, contact the emergency contact of the guest on "Your bookings" on your page. Also, check the message thread. You might get some messages that the guests will be late. Also, if you cannot call guests, send a message to guests.
Then, wait for a while. It may be just a little-delayed arrival due to transportation delay. If you do not see guests after waiting for a while and you need any help, please contact us via email.