Volume light

Make a large box to enclose the scene. This is essential to capture the volume.

You do not need to reverse the normals.

Apply a transmat material to the large box. This is essential to enclose the volume effect.
The box itself will not be visible as a result of using this material.

Create a preset halogen spotlight aiming straight down.

Select a Light shader for the spotlight:

Instance a copy to the material editor.

Make it a bright color.

Turn on shadows in the light shader:

This is the material for the sphere:

In the renderer tab, we have selected a volume shader:

Instance to the material editor:

The only thing I changed was the scatter color:

Render with Draft setting Final Gather:

(Alternatively, you could turn on photons and turn off final gather)

This has a default standard Max material on the plane:

For fun, I applied the default DGS material to the plane here: