Even if it comes bundled with your mobile subscription, then you still have to sign up for it, and link your Apple ID and mobile account.
About bundling Apple Music through mobile phone service providers - Apple Support
How to link your Apple ID and mobile number - Apple Support
Verizon Unlimited Plan Users Get 6 Free Months Apple Music - Verizon Wireless (click ‘Learn More’); vzw.com/applemusic
If you previously subscribed to Apple Music through Apple directly, then you will have to cancel that subscription separately, as both can (or could) exist at the same time. If you ever want to cancel the subscription through Verizon, then you have to contact Verizon about that, as this new subscription is administrated with them.