This article explains how to use Audio Visualizer.
1. Replace music
2. Place an audio file into the placeholder after import
3. Click the “Edit” button 
4. Select an audio file
In case you would like to do it manually.
5. Double click on the imported composition 
6. Double click on the Audio Placeholder 
7. Import your audio (File – Import – File)
Drag n drop your audio to the composition so it’s the first layer. You can remove the placeholder audio layer.