To install this plugin you can use Vundle or another plugin manager for Vim:

Plugin 'hashicorp/sentinel.vim'

Once the plugin is loaded files with the extension .sentinel will be syntax highlighted according to the language specification. To enable formatting of Sentinel files on save, download and install the free Sentinel simulator from the following location https://releases.hashicorp.com/sentinel/0.1.0/ and save it somewhere in your path. When a file is saved the plugin will run sentinel fmt with the current buffer.