Hi,
To use B2M, you just need to drag n'drop the sbsar in your asset folder, and use an image in the "Bitmap Diffuse" input (in your example, I used "water_well_D").
Be also sure to enable the "Specular in alpha (to enable with Unity)" and the resolution in the Substance parameters to have something correctly setup.
You can directly use the material of the Substance, or use your B2M outputs in another material (just drag n'drop the "Bitmap2Material2_Diffuse" and "Bitmaps2Material2_Normal" in a new material).
That's what I did for the "water_well_Mat_B2M_Outputs" material.
Here is a unitypackage than contains a modified version of your scene (I just made a quick setup just to give you an idea, you can of course change how it looks by modifying you Substance parameters). You can import it in a new project using "Assets=>Import Package=>Custom Package". I also add a preview screenshot.
Cheers