For Amuse, YouTube is three things: YouTube Content ID, YouTube Music, and YouTube Topic.
YouTube Content ID lets you earn money on your music on YouTube.
YouTube Music is Google's new music app and a part of YouTube Premium (formerly known as YouTube Red). All music on Google Play Music is included in YouTube Music. So when you deliver music to Google Play, you will also have your music on YouTube Music.
YouTube Topic is an auto-generated channel by YouTube. YouTube usually adds new and undiscovered artists to a channel called "Various Artists - Topic". When the artist becomes more popular, a new hashtag (#) channel with the artist own name will be created. But for starters, the artist would share the channel "Various Artists - Topic".
You can always add your own music to your own YouTube channel.
Read more about YouTube: How do I monetize on YouTube?, Why do I get copyright claims on my YouTube video? What is YouTube Content ID?.