By default, it makes complete sense to prevent downloading, but an option has recently been added to permit it (though without an option to watermark).
In the owner's view of LrWeb, go to the collection and its share settings. In the Options section is a setting to allow downloads.
When someone else is browsing that collection's images in their web browser, a download button is then available in the right hand panel:
It's only one image at a time.
I'm SO grateful for your help - thank you!..... Except that I have just searched everywhere for the past hour looking for the "owner's view of LrWeb" I can't find the share settings in the collection and therefore no "Options" either. I really didn't want to appear stupid - but I'm genuinely out of aces here! The menu you've screenshotted above is using a cloaking device on my Mac!
OK, in your web browser log into LrWeb using your Adobe account - that's the account owner's view and lets you see all collections. You can go into any collection and you see its thumbnails in a brick-like pattern of rows. A "shared view" is what your client sees, only lets the visitor see a single collection, and the thumbnail grid is in a columnar format.
So log into LrWeb and you should see that share icon.
Hi John - just found it! - - But, if you're interested, here's what I was doing:
If you click on the link which is "open in browser" inside LR (top right) it launches the shared collection in your chosen browser. It shows you the collection but denies you the option to do anything with it. It also denies you the option to go a level up to see all your collections. A page I'd never seen before! - I got there by signing out and back in again and it took me to this page where the options above (in your screenshots) ARE available. It seems strange that viewing a shared collection in this way won't allow you to move to an upper level where one can access these options. I've bookmarked this collection page now - so I won't use the "open in browser" option within LR again. Thanks though. Learning journey!
Did you also notice that you can right click a collection and the Lightroom Mobile Links context menu gives links to both the private (owners) and public (shared) views?
Oh yes! - Thanks once again - what a great service this is.... and what great support you've been! - I am now fully removed from my days of Apple Aperture! - A process which only took a few days and things are SO much better for it.
Just some empathy for Spiketrain here - it's not intuative that to download an image that you have to open the sheets on the right, and click photo info to download an image. I've just gone on the same voyage of adventure when a client asked me how to download the image I'd presented to him.
And I've been using the right click on the collection - but now discovered the short url at the top right of the grid - never noticed it! And a big make private button - which could come in handy....
putting the download icon next to the heart/comment icons when the image is displayed would seem a lot easier....