You will probably find your pen drive is already formatted to either Fat32 or ntfs either can be used, however, note file size limit for FAT 32 is 4GB.
Having said that a USB 3 device that is USB 2.0 Should also be just as OK as a plain USB 2.0 memory device. work with it. I not only have exported recordings to USB 3.0 hard drives but have also updated the software using a 1TB USB 3 hard drive that was USB 2.0 compatible and was formatted FAT32.