It is impossible to copy from an external pen drive or ssd to an internal hard drive SSD, but you can copy or delete sound sources in the PC to the SSD built into the Rose device.
Please see the link below.
For Window: www.youtube.com/watch?v=Jps4ZFSoWYI 2
For Mac: www.youtube.com/watch?v=D7xz-ShEpnM 5
I am a HiFi Rose RS130 user.
Is there a way to delete folders or music files individually from the file manager without formatting the SSD installed in RS130?