Virtual Avatar is for users to use Live2D model as avatar in Live Stream. You can use microphone to syncronize the model mouth, and set hotkeys for model motions and expressions to trigger them manually.
How To Use (with OBS Studio)
Connect microphone device to your PC
Start Live2DViewerEX in Desktop Mode and load a Live2D Model
In Widget page, enable 'Virtual Avatar', you will see a microphone icon on desktop
Click the microphone icon to enable microphone, say something to test if it works properly
In Tray setting, confirm the option 'Compatible with OBS Studio' is checked
Start OBS Studio, add a Window Capture source, select Live2DViewerEX (lwservice.exe or lw.exe) window
Add a Color Key filter, change Key Color to Black (#00000000)
Now you can see the model is in front of all sources
You can also set hotkeys for motions and expressions to trigger them manually when you need