If you wish to record system audio using the Mac application, here are the steps you should follow.
Step 1: Launch Vmaker and click on preferences (the three dots on the top right side of the app)
Step 2: Turn on system audio
Step 3: Mute your microphone input on the application
Step 4: Start recording!
NOTE: You can also choose to record system audio without muting the microphone input but please note that the input audio from your microphone will overlap with the system audio recording.