Spotify client id and secret from here.
Spotify account name and playlist id. (Playlist id is the alphanumeric string following /playlist/)
Youtube API Key from here.
Youtube-dl installed on your machine from here.
Open config.js and substitute in your Spotify client id and client secret, as well as your Youtube API Key.
You can specify the directory you wish to download the playlist to in config.js. If the directory is not specified, spodl will download the playlist to the spodl directory.
After this you can then run spodl spotify_account_name spotify_playlist_id