Looking at the booking page, it asks for my flight arrival time. How exact does that need to be? I.E., the actual flight arrival time, or estimated time we would be ready to board shuttle?

Hello John & thank you for your question. You can put the actual flight arrival time. This helps us consistently estimate transportation needs. Shuttle service is a walk up service at the airport so if the flight is delayed it won’t be an issue. We look forward to serving you!

Actual flight time, I think you put in your flight number when you book.

I'd say actual flight arrival time. After you arrive, you go to their station to grab your tickets. If anything, you don't have to buy the ticket prior to landing. I bought mine after I arrived.