This is a basic question. Auditing is not like regular accounting. There will be programs that most people have not heard of. Basically, anything that affects the company can be audited, i.e., financials, health insurance, IT compliance, etc. You'll run into so many different systems that those you use at one company may not be the same at any other company you work with.
If you don't have any experience with any platforms, admit it. Honesty is always the best policy.
"I've worked with Peoplesoft, Blackline, HR Passport, Service Now, Xactly, and various others."
"I've never worked with a platform related to auditing. I'm just out of college but I'm a fast learner and am told I'm easily trainable."
"I've worked with several platforms to audit them ranging from Peoplesoft financials to HR Passport to Informatica. There are so many I couldn't tell you all of them in one sitting. What platforms does your company utilize?"