First of all, you must have a certain foundation of music theory knowledge and be able to read music. If you have studied piano, you will be fine.
In the interview, you must first introduce yourself and tell me that you particularly like music. That is ok. You must talk about your music learning experience, and then you will definitely be tested on some basic music knowledge. You will be given a piece of music to sing or play, and you will be asked about your music learning background, etc.