I'm not sure what /findmob does, or at least I'm not familiar with that command. I tried to copy all the existing commands, so maybe its part of another plugin?
You can try /nav target, that will navigate to your target.
The mesh file downloads were created for the old version of MQ2Navigation. They'll need to be created for each zone you use it on.
We really need to start a new project of making meshes for new version of MQ2Nav.