Help! I purchased Apple Music and it will not allow me to play or download music bc I hit “remove this device” from under iTunes in the iCloud

Sign into iCloud on the device and turn on find my iPhone (renamed Find My in ios13)

Add an iPhone, iPad, or iPod touch

For a device with iOS 13, iPadOS 13, or later, follow the instructions below. For a device with iOS 12 or earlier, see the Apple Support article Set up Find My iPhone on all of your devices.

1. On your iPhone, iPad, or iPod touch, go to Settings  > [your name] > Find My.
2. If you’re asked to sign in, enter your Apple ID. If you don’t have one, tap “Don’t have an Apple ID or forgot it?” then follow the instructions.
3. Tap Find My [device], then turn on Find My [device].
4. Turn on any of the following:

• • Enable Offline Finding: When your device isn’t connected to Wi-Fi or cellular, Find My can locate it using Bluetooth.
  • Send Last Location: If your device’s battery charge level becomes critically low, its location is sent to Apple automatically.

More info:

https://support.apple.com/en-ca/guide/iphone/iph09b087eda/ios

• Once you've done that make sure to Turn on Sync Library with Apple Music

https://support.apple.com/en-ca/HT204926