If you started the trial the day it became available, they charged you yesterday.
How to cancel.
I somehow opened a spotify account years ago associated with my Facebook login. Now they won't let me start a new account because my everyday email was associated with my Facebook account back then ("that email is already in use" is the message I get) . F that- I just want to use my regular email as a login and have Spotify have nothing to do with my Facebook account. Impossible.
So Apple Music by default for me.