Enterprise Rent-A-Car

from the arrival, you have 3 options. 1. You may take a Taxi to the rental site (super fast if in a hurry); 2. Take uber or lyft from the middle lanes accross from arrival labelled 2E-2F (Also fast but you need to have account with uber or lyft); 3. Take a free ride with the rental car shuttle from the area across from arrival labelled 3E-3F (This option is completely free to the rider)

You may want to communicate with car rental agent. Online states shuttles on call from something like 1:00am-4:30am. Agree should be prepared with back up ride alternatives just in case.

They ask for return flight confirmation for debit cards.

Quickest and cheapest would be to take the shuttle to the airport. There's a Bart station there.

Not sure you need to check on that

Shouldn't you contact them directly?

Check the website or use the app.

you have to negotiate with them. they may need to get a car returned.

The locations can pick you up and take you to the rental car center and then you can drive off

They might have someone working 24 hrs at the kiosk inside the airport. Otherwise, the outside pavilion is closed after midnight.

There are shuttle buses going round trip between the airport and the car rental facility. You catch the shuttle bus in front of rental facility and in front of airport in the middle median.