The ChargePoint app and website report the ChargePoint L2's are free, open 6am-midnight, 7 days/week. You'll need to activate the station with a Chargepoint RFID card or phone app, assuming you have a ChargePoint account, or a voice call to ChargePoint if you don't.
The Superchargers are only free if you have free Supercharging. Supercharger pricing policy is the same at all (US) stations; if you have free Supercharging, it's free at all stations. If you pay at one, you'll pay at all.
EDIT - I'm pretty sure all Superchargers have the same idle fees - I've never seen on that doesn't.