The installment is not hard at all. Assuming that you use a POSIX compliant shell: You start by downloading or cloning this repository and move the file into your home directory.
cp .vimrc ~/.vimrc
After the installation, you need to install vim-plug by running the following command.
curl -fLo ~/.vim/autoload/plug.vim --create-dirs https://raw.githubusercontent.com/junegunn/vim-plug/master/plug.vim
Then open vim and install the plugins with :PlugInstall.
Please be sure that you have NodeJS and Yarn installed.
Run make install to do it automatically.
It's because you don't have a Nerd Font installed. After installation, adjust the .vimrc and reload the configuration through :source ~/.vimrc.
If it still doesn't work, see if you can specify a font in your terminal. If so, select the Nerd Font there.
Install a coc extension. The instructions for the extensions as well as how to install them can be found here.