How to do pathfinding on C++ Server?
This is a package for Unity written primarily in C#, so unfortunately it does not run using C++, it requires Unity to run.
If i have nav meshes, Is there any algorithm to do pathfinding in C++?
There are tons of C++ pathfinding libraries, just google for them. Or if you want to write something yourself, the core A* algorithm is not many lines of code.