Clone it :

git clone https://gedmin.as/dotvim ~/.vim

Then install all the plugins (this'll be an interactive) and compile C extensions (e.g. for Command-T) :

make -C ~/.vim

A common piece of advice given to new Vimmer is

Don't put any lines in your .vimrc that you don't understand.

I completely agree with it. Don't use other peoples' vim configs wholesale; instead look at them, browse for ideas, then copy the interesting bits one by one.