For that you need to choose the option save to desktop rather than libraries.
The image will be downloaded to your downloads folder , from there you can open the image in your external editor.
Thanks you Jitendra, for prompt reply . . but that is EXACTLY my problem. . .I have 3 options . . .none of which ae to save to desktop. . . . only to libraries or Cloud. On my very first try to download, there was a text box with instructions for desktop download i.e. click here - but that link was not active/live so I used a Library option . . which is fine, the download is visible, but I can't export it anywhere . . .and that desktop download box box has never appeared again.
I will - reluctantly - be cancelling my subscription if I can't access my downloads . . . a no brainer really!
It's okay . . . I've figured it out . . .thanks for your help, it put me on the right track
You are Welcome