Your MIX 2 features a microSD memory card slot. If your personal computer is compatible with that type of card (Most laptops are so-equipped), you should be able to save a music file
The Ulefone MIX 2 is an Android phone and there are plenty of free ringtone apps such as MP3 Cutter, RingDroid (open source) and more.
Here are some of the free ringtones (Ulefone MIX 2-compatible) offered here at MartinsRingtones.com:
Free Horror MIDI Ringtones Free Ghost Ringtones Free Ringtones-a-gogo Free Techno Ringtones Listen To All Our Free Polyphonic Ringtones