Once you have imported the .unitypackage file into your project, locate the Game Board 19x19.prefab object and bring it into your scene.
The following additional steps are required for the game board to work:
The Edit Layers menu showing how to set up layer 23.
Project Settings window with the Physics tab selected, and the required checkboxes.
The VRC Scene Descriptor with Reference Camera slot highlighted
The script properties on the Stone Pickup W and Stone Pickup B objects, with Desktop Camera slot highlighted.