In the md file for plex it says to input the following code block, but doesn't have any, so I tried the one for both windows and linux and it didn't work.
I think the code blocks found in the windows installation guide should work. If you installed plex on a different OS you should use the corresponding code blocks for input.conf.
You can take a look at my step-by-step Windows (GLSL/Plex) guide here.
I think you are confusing input.conf and mpv.conf with input.conf.md and mpv.conf.md.
Those are not the same files, you can use my template in the guide and just drag and drop the config files in.
In the md file for plex it says to input the following code block, but doesn't have any, so I tried the one for both windows and linux and it didn't work.
ps. running plex on windows