Commento ufficiale

One of two things...
1) The drive is not formatted HFS+ or FAT32, which are required for export devices. rekordbox can read from APFS, NTFS, and exFAT, but can't write to them as the players can't read those file formats.
2) Your drive is formatted correctly but you haven't given it permission to access removable devices in System Preferences > Security & Privacy > Privacy