Pick the computer you want your canonical library to live on. Open iTunes. Make sure iCloud Music Library is enabled in iTunes > Preferences > General. Select Music from the dropdown menu, and select the Library tab. Go to View > Show View Options. Click on the checkboxes next to iCloud Download.Can I log in to iTunes from any computer?
If you want to log in to your iTunes account from another computer, such as while you are traveling, you can authorize up to five stand-alonecomputers at any one time to access your iTunes account and purchases. Open iTunes and click "Store.". Select "Authorize This Computer" and enter your Apple ID and password.