Sorry for the delayed reply. Usually, we can transfer music from Samsung to Samsung phone via Drag & Drop on Computer like this:
1. Link two Samsung phones to the same computer via USB cables, enable USB debugging on them.
2. After the computer detects your Samsung phones, double-click My Computer from desktop, and double-click source, and target Samsung phones to open them.
3. Select music files from your source Samsung and drag and drop to another Samsung phone.
You can also do that via Smart Switch, Bluetooth, or using Phone Transfer software. Actually, it's not that difficult. Hope this will be your help.