Your Mate 9 Pro is equipped with a microSD memory card reader. If your laptop or personal computer can also read that kind of card (Most laptop computers are so-equipped), you should be able to transfer music files
The Huawei Mate 9 Pro is an Android smartphone and the Android market offers a bunch of free ringtone apps such as MP3 Ringtone Maker, Myxer and more.
Learn more about making your own free ringtones
Here is a sample of the all free ringtones (compatible with your Huawei Mate 9 Pro) we offer:
Free 'Unclassified' Ringtones Free Ghost Ringtones Free Short Ringtones Free Far West Ringtones Hear All Our Free Polyphonic Ringtones