Once the scene is complete create your mesh from the Mesh tab.
Select mesh and drag from 2.5dToolKit/Shading: MatteShadow material to Element 0 of Mesh Renderer
CustomTransparentShadowCollectorVal on Shader of MatteShadow
For maximum performance select Directional Light and set Resolution of Realtime Shadows on Very High Resolution.
If shader does not work you can try the others. Keep in mind that materials for obtaining shadows are for demonstration purposes only. You can search for better ones or write your personal ones.