Making a Shader receive Shadows?

Complete newbie to shaders, was following along with this tut:

. the shader seems to work good but objects with the shader applied to it don't seem to receive shadows.

Shadows when the ground doesn't have a shader: Shading with Shadows https://imgur.com/gallery/kHueJcN
Shadows when the ground has a shader: Toon Shading with no Shadows https://imgur.com/gallery/qIWwrUE

Can anyone help me determine what is going wrong? I've tried a couple other sources and fixes but still haven't found a solution.

Thanks in advance