I suppose you know all of this but just to be 100% sure - quote from the Main Manual:
• Before you can use a USB memory stick to transfer files from your Mac or PC, your USB stick and PROFILER need to become acquainted. When you connect a USB memory stick for the very first time, the PROFILER will create three folders on that stick: “Backups”, “OS Update”, and "Shared”. As soon as “USB Stick” appears below soft button 3, the USB memory stick is ready to go
• New USB memory sticks are normally pre-formatted with file system FAT32, which is immediately compatible with the PROFILER. In this case, no further action is needed. If you plug in a USB memory stick pre-formatted with another file system, like NTFS or exFAT, the PROFILER will automatically suggest reformatting the stick with file system FAT32. Be aware that this formatting will delete all data on that stick! Once the formatting is complete, the PROFILER creates the three folders and “USB Stick” appears below soft button 3. Ready!