Getting audio input from every application

How would I get an audio stream from every application that is outputting audio? like how the windows mixer does it.

I am new to C++ and JUCE (I have done a bit of Java and C#), so please be rather verbose.

The windows mixer is able to see the audio that every application is outputting

you can’t do that directly, but you probably want to look into the windows audio APO docs:

check Equalizer APO download | SourceForge.net for another project that does it. pretty sure there are per-app and post-mixer API options.

I found an article that, with a few modifications, will do exactly what I need it to.
The article: Application loopback audio capture - Code Samples | Microsoft Learn
I have tested that it works.