On MacOS or OSX, the file system will add hidden files for housekeeping purposes. Many embroidery machines cannot work around these files, if they’re present on the drive being used by the machine. The workaround is to remove them, which you can do manually (if you can see the hidden system files on your Mac) or have the Platform do it for you automatically (provided your system has permission for this.)
Option to remove hidden and system files when writing removable media.