How can i buy a song from apple music on my galaxy s22

First, you have to download and install the Apple Music App from the Google Play Store. Then you have to setup a payment method by entering a credit card or bank account. Then select a song in the iTunes Store section and buy it. Or subscribe to Apple Music to listen to anything you want to.

Then you are not subscribed to Apple Music, period, you only think you are. An Apple Music subscription gives you access to all content on Apple Music. Using Android has nothing to do with anything.