Hi there,
Thank your for your inquiry, hopefully my answers can clarify a few things.
The Audio Component you are using in the blueprint is not related to the microphone component of Pixel Streaming. To be able to pass the microphone data from the stream back to UE, you need to add the Pixel Streaming Audio component to your scene. You can essentially attach it to any asset or actor in the scene as per below:
Once you’ve done that, you can adjust its settings, say, to pick a particular player to listen to, but the default configuration will work out of the box, where it will default to the first peer it can hear:
You are ready to roll. Start streaming your application, enable the microphone in the settings panel by toggling the Use microphone setting, and then restart the stream; you should now be able to hear your own playback.
Note, that all this component does is pass the audio data back from Pixel Streaming to UE (which is why you can hear yourself). If you need to further pass this audio stream to another plugin or utilize it for any other purpose, you will need to customize the application.