Some rental car operators are taking a deposit and bond as security. In most cases, the deposit is required to secure the booking and some rental car operators will take the insurance excess/bond up front while others will only take an imprint off your credit card. Either way the total will be refunded when you return the vehicle and if you do not have an accident.
This is facilitated directly between you and the rental car operator after you have been accepted as a driver. You provide them with your credit card details and they will take out money from your credit card or place a hold for the the amount, which is then refunded when the vehicle is returned.