Learn more about Emby.
You can create an API key from inside Emby at Settings > Advanced > Api Keys.
As of v0.6.11 the widget supports fields ["movies", "series", "episodes", "songs"]. These blocks are disabled by default but can be enabled with the enableBlocks option, and the "Now Playing" feature (enabled by default) can be disabled with the enableNowPlaying option.
widget:
type: emby
url: http://emby.host.or.ip
key: apikeyapikeyapikeyapikeyapikey
enableBlocks: true # optional, defaults to false
enableNowPlaying: true # optional, defaults to true
enableUser: true # optional, defaults to false
enableMediaControl: false # optional, defaults to true
showEpisodeNumber: true # optional, defaults to false
expandOneStreamToTwoRows: false # optional, defaults to true