Hi
Currently, there is no interaction between unity tilemaps and the A* Pathfinding project, I’m afraid.
One thing that can be tricky with Unity hexagonal tilemaps is that they are, in fact, not hexagonal. They are slightly shrunk along one dimension.
This post might be of help to you: Help Matching the Hexagon Grid Graph to the 2018.2 2D Hexagon Grid (sorry that I still haven’t implemented functionality to match the settings automatically).