How Do I Enable iTunes Match On My iPhone?
Once you turn on iTunes Match in iTunes on your Mac, you can setup iTunes Match on any iOS device. First, launch the Settings app on your iOS device. Then select Music and switch on iTunes Match. You will then be prompted to enter your Apple ID password.
It's important to note that iTunes Match will replace all the music on your device with tracks you have uploaded to iCloud. If you have second thoughts after turning on iTunes Match, the Settings app will warn you that your music library is about to be replaced. Choose Enable and you're all set!