The first error message "The files could not be copied to the backup location" signifies that the location which you have chosen for the second copy of your original images does not have full read and write permissions.
So, you need to check if that location is specified properly.
Regarding the export issue, watermark option has not been removed and it is still there in the export menu.
Did you scroll down in the export settings window to look for that?
Which format did you choose for the export process? Is it set to original by any chance?
A screen capture of your export window settings would be helpful here.
Like Chetna asked, are you exporting original? Yes, you are. That's asking to export a copy of your original file, which is, of course, unmodified. So, yes, you won't see any of your edits. That's why you can't apply a watermark. Adding a watermark to the image would make it a non-original file.
Choose another value for Image Format under File Settings.
Thank you so much Hal. So simple to resolve when someone explains it so clearly.Thank you.