Unable to Stream Audio via OBS Studio for HoI 4

OBS is not picking up game audio since the audio mixer is set all the way to the left. Drag the slider for Desktop Audio all the way to the right, or at your desired volume. That will allow your OBS to capture the game audio.

OBS must be run with Administrator permissions in order to hook into the full screen rendering process.

So right click on the shortcut for OBS and click "Run as Administrator". This is tedious to do repeatedly, so, instead, right click on shortcut and click "Open File location" and do this over and over again, until you find the original .exe file in Windows Explorer (not a shortcut), then right click on the file, and click on the "Compatibility" tab, and then check-mark "Run this program as an administrator" and click "Apply" or "OK".

I discovered the answer in a Youtube comment on a video. The video itself did not have the answer. There is no competent answer anywhere else on the internet. The game is League of Legends, and running it in Windowed-Fullscreen is not an option.