Your iTunes match subscription will only apply to your account, not to other accounts you might have in Family Sharing. When you download content that you didn't buy with your own account, it will count towards your 25,000 song limit.
When you add a computer or iOS device to iTunes Match, you'll associate that computer or device with the Apple ID you use for iTunes Match. You can associate up to 10 computers and devices (combined) with your Apple ID. Learn more about associating a device or computer with your Apple ID.
Add your computer to iTunes Match
- Open iTunes on your computer. Make sure you have the latest version.
- Sign in with the Apple ID you use for iTunes Match.
- Go to Store > Turn On iTunes Match.
- Click Add This Computer.
- Enter your Apple ID password.
iTunes will start matching and uploading your library. You'll see progress in the progress bar, and you can pause and resume this anytime. When iTunes is done, your music in iCloud will be added to your local music library. You'll see a download button next to any content you have in iCloud that hasn't been downloaded to your computer.
Add your iOS device to iTunes Match
To use iTunes Match, you need iOS 5.0.1 or later. To turn on iTunes Match, go to Settings > Music.
Your music in iCloud will be added to your local music library. When you open your Music app, you'll see a download button next to any content you have in iCloud that hasn't been downloaded to your device.
When you turn on iTunes Match, the music library on your iOS device will be deleted and replaced with your music in iCloud. Your device might use cellular data for this download. Check with your wireless carrier for fees that might apply, or go to Settings > Music and turn off Use Cellular Data.
You won't be able to sync music with iTunes while iTunes Match is on.