I tried all the releases.
I’m not sure if the new mGear 3 is supported in 2016 or not. In one comment, Miquel said it should be easy to fix, which seemed to mean it wasn’t supported yet. mGear 3.0.3 available
Did you try the older 2.6 releases? They should definitely work. https://github.com/mgear-dev/mgear/releases
Have you tried installing on newer versions of Maya 2018 or 2019? Just to make sure there is not a problem with the way you are installing mGear?
Otherwise, can you please explain how you installed mGear, just to make sure there are no problems there? And what operating system? What actually happens when you launch Maya? Does the menu just not appear? Do the solvers not work?