After having both AC and A*Pathfinding in your project. Install the integration package.
AC (1.4.0) AStarPathFinding (4.2.18).unitypackage
1.- On your scene, make sure you are using Recast Graph, since it's the graph that has Offmeshlinks the Animal Controller can use to move off meshes.
1.- Select any of your animals and unpack the prefab. That way you can remove the Animal AI Control, and replace it with the AIControl (A*) Component. Remove also the Unity NavMeshAgent component.
This will add automatically the Seeker and the RichAI components from A*Pathfinding.
2.- Add the A*Modifiers you need to improve the Pathfinding on your AI
And that's it :)