Hello,
The ‘not signed’ indicator is letting you know that the Shaderlight extension hasn’t been verified and digitally signed by Trimble. Unfortunately, Shaderlight isn’t compatible with SketchUp’s signing system, so it will always say this. It doesn’t affect Shaderlight’s ability to work, though, as long as you allow unsigned extensions to load, which it sounds like you have done, since you were able to access the activation dialog.
Can you describe in more detail what doesn’t work?
Many thanks,
Shaderlight support