I would like to make my website as mpmudev's blog page

I did not install any theme yet.
I was found this site on the google.com and just i like your blog site.(https://premium.wpmudev.org/blog/)
Which theme should i download to build up like that?
I would like to build my site quickly, similar with this blog site with theme(includes css, jquery, javascript and so on ) like getbootstrap.com does.
Is it possible? or not, how can i leave membership?
Please let me know.
Thank you.