Your Galaxy J3 2018 features a microSD memory card slot. If your personal computer has a slot for that type of card (Most laptop computers are so-equipped), you should be able to save music files
The Samsung Galaxy J3 (2018) is an Android phone and there are plenty of free ringtone apps such as MP3 Cutter, Myxer and more.
Here is a sample of the free ringtones (Samsung Galaxy J3 (2018)-compatible) offered here at MartinsRingtones.com:
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