If you copy the regular audio files to a Flash drive, you will only end up with a set of files there. They are not in any "order" – they are just files on a drive just like all files in a folder.
So it's up to what you use to view or play the files to sort them. For example, in the Finder you can see files sorted by date or name or size, etc. If you use something to access the drive, it will be up to that device to decide which order to display or play the files.  Having said that, it is a good idea to put numbers in front of the file name. Not the song name, which is the metadata in the file, but the file name itself. So you may need to export them and then rename the files in the Finder on that drive.
I'm not sure what you're doing from there, so it's hard to inform further.