how to get the free music trial

Usually, Apple provides a free trial of all their paid apps like movies, and iTunes for a 1 month from a certain time of purchase of your device, when the time expires you need to purchase the subscription plan from their application or website Apple Music - Apple (IN) you can cancel this subscription at any time

If you are eligible it will show in Settings > [Your Name] > Subscriptions on iPad/iPhone.

On a Mac go to System Preferences > Apple ID Media and Purchases > Subscriptions.