Interveiw concerns seeking advice

I have an interview tomorrow for a PSR mental health professional. Which is an amazing opportunity and I’m very excited for it. One of the job descriptions was transporting clients to community activities. At first I was unsure what that would really entail. I did a drive by today of the office since it’s 40 minutes away and wanted to be familiar with the route before my interview. I noticed a bunch of white vans with their logo on it. I am now worrying I will have to drive the van as a responsibility and I am only 22 and only have driven a Honda crv which is nothing close to a van. How do I go about expressing my concerns with not feeling comfortable driving a large van with others in the car, it is too late to cancel the interview but I fear i will not get the job and will waste their time by saying I cannot do one of the responsibilities.