This is a paid asset, but now you can download Twitch Live Stream Player – For HLS players for FREE, but please remember this package is provided only for learning purposes or to be able to test before buying the product, NOT FOR COMMERCIAL PURPOSES.
Detail this asset from Unity Store: Original Link
Twitch Live Stream Player – For HLS players v1.6
Play Twitch livestreams inside unity using a HLS player.
* You need one HLS player plugin, like Easy Movie Texture, AvPro, UMP, VLC player for unity, etc… Unity Native Player Dont Support HLS playback.
You just need to put the twitch channel id in the field of the player and the video will play.
The desired livestream channel need to be live to work.
*This is not a official twitch release. Its a tool made by lightshaft for unity users.