There are a couple of options for your question.
Contact the loan company. Before you do anything, you should check with the loan company to see if they have any insurance requirements. Some loan companies have strict requirements because they have a vested interest in the car, until it is paid off.
If there is insurance on the vehicle now, you can be added to the existing policy. That would mean you would have to cover the premiums for the insurance on that car and cover the premiums on your policy. I will assume you want one insurance and one premium.
Most insurance carriers normally do not care if you are paying the loan or not. What they are concerned about is making sure that the policy has a licensed primary driver listed, she is listed as a secondary driver and the vehicle resides at your address. If there will be any other persons that will be driving, it would probably benefit you to list them as well, as long as they are licensed. Most insurance companies will give you a discount for multiple vehicles.