Hello Beingellenking,
Welcome to the Apple Support Community! We understand Apple Music has been crashing on your Samsung A20s, causing you to have to uninstall the app. We also understand you have questions regarding cancelling your Apple Music subscription.
You mentioned that you're still unable to log into Apple Music. Based on that infomation, it sounds like you've followed the steps from "If you already subscribe to Apple Music" from this article: Join Apple Music on Android.
If those are the steps that you've followed, what's happening when you try to log in? Are you receiving an error message?
Since the issue is with logging in, begin by verifying that your Apple ID and password are working as expected. Go to the Manage your Apple ID page. You can access this page from a web browser on any device, including a computer.
If you're able to login with your Apple ID and password, you'll next want to check for any outages in your region: Apple - Support - System Status.
If there are no outages, verify your internet connection by going to a homepage in the web browser of your phone. If you have a good internet connection, and the issue persists, try on another network. If you still can't connect, Contact Apple Support for further assistance with logging into Apple Music.
If you still wish to cancel your Apple Music subscription, you'll want to follow the steps from this article: See or cancel your subscriptions
Take care.
