< help / plugin doesn't show meters
MiniMeters is not designed to be a plugin. Instead, MiniMeters is a standalone app that can accept various audio sources including a DAW with the included MiniMetersServer plugin.
There are many advantages to MiniMeters being a standalone app. Primarily removing the window borders, automatically restoring the position at launch, and being persistent between projects.
Ideally MiniMeters should be used with a loopback device such as an audio interface that supports loopback, a program that sets up a software loopback (on macOS mainly), or with an audio output capture (on Windows).
The advantage to these methods is the ability to not only monitor your DAWs audio but also everything that is coming out of your speakers. This can help build insight to what you are seeing on your own productions.