OK you lack the experience but are being interviewed for the position anyway.
Don’t try to fake your way through the interview, stuff like that comes to the interviewer/s attention real fast and is a deal-breaker.
Stress that you are “number-oriented”, by this I mean to point out that you are good with arithmetic. It sounds trivial but it is important, lots of people can’t add or subtract to save their lives.
Stress that you are organized, that you can think logically and that you are a fast-learner.
To my mind, an accounting assistant’s job is not the same as a junior accountant. This job title indicates something that involves clerical tasks as well as accounting tasks.
Look, no one is going to assign complex accounting problems to you if you don’t have the fundamentals, at least I wouldn’t. So don’t worry about your lack of accounting knowledge, that is not what you are being interviewed for, at least not in my opinion.