If you use Vim 8 or later, the recommended way is using Vim's built-in package manager:

git clone https://github.com/udalov/kotlin-vim.git ~/.vim/pack/plugins/start/kotlin-vim

• Vundle
  • add Plugin 'udalov/kotlin-vim' to your ~/.vimrc and run PluginInstall.
• Pathogen
  • git clone https://github.com/udalov/kotlin-vim ~/.vim/bundle/kotlin-vim

0. mkdir -p ~/.vim/{syntax,indent,ftdetect,ftplugin}
1. cp syntax/kotlin.vim ~/.vim/syntax/kotlin.vim
2. cp indent/kotlin.vim ~/.vim/indent/kotlin.vim
3. cp ftdetect/kotlin.vim ~/.vim/ftdetect/kotlin.vim
4. cp ftplugin/kotlin.vim ~/.vim/ftplugin/kotlin.vim
5. If you use Syntastic: cp -r syntax_checkers/kotlin ~/.vim/syntax_checkers/
6. Restart Vim