Hi It seems to me that if you install just the theme and not the quickstart you don't get GK Grid. You get Grid overlay but not the Grid widget. This is a bit annoying !! If it's me sorry but I just can't find it! Thanks
remember to unzip first and upload only gk-grid directory into wp-content/plugins. (it's plugin so can't be placed with theme files, you can also copy it from quickstart package, but on the Github you have always the latest version).