The Meetup app has unfortunately been discontinued. The good news is we've got a new app in development that should come out later this year - it'll let you view your trip, bookings, chat to fellow travellers and all the amazing things you'd expect from an app. Keep your eyes peeled for that one.
In the meantime, the best way to get in touch with your group before your trip is on our Facebook page. Just write a public post with your trip name and date.