Clone the repo into ~/.vim/pack
git clone https://github.com/janospapp/vim ~/.vim
cd ~/.vim
git submodule init && git submodule update
or simply
git clone --recurse-submodules https://github.com/janospapp/vim ~/.vim
Then create a symlink of .vimrc to your home directory
ln -s ~/.vim/.vimrc ~/.vimrc
git submodule add <github repo path> pack/plugins/start/<plugin-name>