Why is this template not available anymore?
Because it's totally outdated now and not recommended to use. The last version (v4) of this standalone Metro Webdesign template was created around 2013 and it built upon the foundations of v3, made in 2012.
At that time, web development was totally different from now. Fancy frameworks like Bootstrap or AngularJS were not as comprehensive as now. Version 4 still has a separate desktop and mobile site, something that's unimagable now but it was required when mobile processing power was so limited.
Furthermore, do you notice the /#!/ in the url? The template implements the Google AJAX crawling specifications. The AJAX was needed for the page transitions, eliminating the need of a page refresh. But this technique is also totally outdated now. Have a look at the newer Wordpress template I created, which uses the -at the moment- proper technique. It makes use of the History API in browsers. Much nicer!
The use of image icons is also not recommended anymore, so better use Fontawesome or some alternative, just like in the Wordpress version of this template.
And to finish, the design is already becoming a bit nostalgic :) The horizontal-scrolling tile page is somewhat strange, and even Microsoft realized that it's not so intuitive. So in Windows 10 we're back to vertical scrolling.