Just went to the Pack Station website and here is what I found:
The road to Chantry Flat is open from 6:00 AM to 8:00 PM. You can buy your Adventure Pass (often called the “parking pass”) at the Pack Station on Friday, Saturday, and Sunday. When the Pack Station is closed, you are welcome to park in the Pack Station lot and put $5.00 in the Pack Station’s Honor Box. The Honor Box money goes to buy feed for the donkeys and the goats. They greatly appreciate your donations.
Sounds like you’re good to go!
Have a great hike!