Hi
That isn't an extension I've heard of so I can't really give you much information - it does list k2 in its integrations section
I do think k2 has a star rating system inside the configuration but I think it will probably be insufficent for the way you want to use it.
With components that don't come with their own styling you may need to add new css or in other situations you may need to override existing styling from the template
Cheers
Paul