In that case, she needs to know which directory those music files are in. Use any file manager app to look through all of the user-accessible directories. The file might be in /Download, but it might also be in a specific directory related to the app she used to edit the music. Then:
1. Connect the phone to the computer via USB.
2. Swipe down the notification panel, tap the USB notification, and make sure it's set to MTP (or File Transfer).
3. On the PC, open Windows File Explorer, open the phone's storage there, and look in the directory where the music files are.
4. Drag and drop those files to the computer's hard drive.