How knowledgeable are you about Facebook's advertising platform?
One of the key job duties of an account manager at Facebook is to help businesses optimize their advertising using the company's various apps and services. While you will definitely learn all of the nitty-gritty details about Facebook's advertising platform if you are hired, you'll want to show the interviewer that you already have general knowledge about it. If you've personally used it before (or even a similar service), make sure to talk about that as well.
"I am very familiar with Facebook's advertising platform because I have personally used it before. Although I've always worked for large companies, I have family members who own small businesses, and I have helped them run advertising campaigns on Facebook and other social media platforms before. As a result, I know how to set up, run, and track online ads. I know this knowledge will help me when I assist others in optimizing their own advertising campaigns. These campaigns always brought in a lot of qualified, good leads for my family members, so I'm excited to help other businesses bring in leads using Facebook advertising too."