process goes like this: for sat&sun get a voucher the night before (that morning if it's not supose to be a busy weekend) from the building up the street. There you will need to give them your license plate number and you get a voucher, it's free. The vouchers are for parking lot crowd control - different times for differnet vouchers. Show up the morning and present your voucher
They will ask if you have a State sticker for each machine you plan on taking into the dunes, you say no, they sell you how many stickers you need right there at the entrance booth, $16 each vehicle. Then they ask if you have a daily pass, you say no and they sell one for $6 for all machines, duning or not. then you go on thru.
Then you're in the parking lot either unload or drive straight to the dune entrance booth. they look for state park sticker on machines (the yearly $16 one), LOOK for SA on machines, ask you if you have a cooler and if there is beer in it (they don't even look inside), make sure your flag hits the 10 foot bar and your in.
if you are going on sat or sun get your voucher the night before, that place gets pretty busy on weekends during the main summer months and parking spaces go fast. If you drive straight out there (dune ready vehicle) it's easier but still need a voucher