Currently there's no download available because the engine is not released to the public yet.
A first version of the starLiGHT.Engine is actually being beta tested by our QA-Team.
You can follow the progress in the Changelog and the Roadmap. When this piece of software is released you will find different versions of downloads on this page:

The current stable release

A snapshot of the development branch

A snapshot of the experimental branch (engine developers only)

Further information about this is available on the wiki page about Branching and Release Management Policy. This is a technical documentation for developers but it contains some interesting information about the different releases and branches.