Do it on the website or call them
You can pre purchase on their website or just show up like I do. When on their site you can set up a profile and add your license plate and credit card for a faster exit when you get back. When you get there they will give you a ticket before you board the shuttle. They are not running as many buses so you may have to wait for 5 minutes for one to get back if you are there early in the morning.
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