Detail this asset from Unity Store: Original Link
This is a paid asset, but now you can download Fast Shadow Projector Free.
Fast Shadow Projector v1.5.3
Blazing fast, easy-to-use alternative to the Blob Shadow Projector. This projector can render lots of blob shadows that fall correctly on any surface while still maintaining high framerate even on mobile devices.
* Shadows fall correctly on any surface
* Many shadows on a mesh with one draw call
* Highly customizable: opacity, shape, size, etc.
* Use for Shadow and Light effects
* Unity’s terrain support
* HIGH performance!