1. You need to contact the professor of your major in Germany, send him the works, and then practice the exam repertoire, which is an inevitable condition for your major.
2. proof of class hours is necessary when applying, and it is best to have a Test-daf score before entering school. Some schools even need it when you apply, even if it is not needed, you must make it up within one year after entering school.
3. If your major is OK and the professor says it is OK, you can apply for the undergraduate course for the first semester.
4. If you have no problem with your German, and you have friends in Germany to help you contact professors, you can apply for it yourself, or you can find an intermediary.
5. There are many language schools in Germany with different prices, but if you go from scratch, you will need at least 1, euros in the first year, including living expenses. Therefore, it is suggested that you should have a language foundation before you go. You can go to Beijing New Oriental to learn a full German class in advance, and it will be much better to master a certain language. I suggest you visit official website of German National Conservatory of Music to check the application conditions and specific procedures. Good luck.