I set up an album in “Photos” pics in a certain order. When I transfer them to a thumb drive and open them up on another computer that also has the “Photos” app the order is scrambled. How do I save them to a the thumb drive unscrambled?

Photos allows for images to be arranged ad hoc in an album, but when you export from Photos to the thumb drive you're moving the images from Photos to the Finder. The Finder has no such ability, and can only sort on name or date etc.

So the trick is to rename the images in a sequence, which can be done the File -> Export dialogue, so that they can be arrange din order in the Finder.