That’s a bit of a detail to miss…
Look inside the platforms folder. Look inside the module .mod file. You’ll see there is no 2023. Which means the module won’t install in Maya 2023. You can attempt to add the 2023 paths to the module. And you will also need to compile the plug-in solvers for Maya 2023.
As of this moment, there is no support for unreleased Maya versions.
If you are going to use beta software (and a beta software inside a beta software at that), you should be willing to roll up your sleeves and do at least a little bit of debugging yourself. Otherwise I simply recommend you do not use Maya or mGear beta versions until they are more tested and complete.