Simple, just scan. Recommended in the afternoon so you can watch the Kecak at 6 (sit right in the front, otherwise you won't be able to see it), but it seems like there's a show every hour.
Vehicles or motorcycle taxis can only go as far as the parking lot, there's a free shuttle. It's just that the shuttle, because the ticket you choose is not included, aka the regular one, has a very different time span from the one that is included, so you have to wait a bit longer.