That option should still be there, so I guess we need to figure out why you think it's not.
So, presumably you have checked the album share settings to confirm that the downloads option is enabled?
Then, are the people that you've shared the URL with reporting the issue, or is it you checking your own album? If it's other users, did you send them a specific invitation via email or did you just send the URL?
Do they have their own Adobe account?
If you are checking your own album, how are you viewing? If using your own main LrWeb portal (i.e. with all photos and albums listed and the specific album selected), the download all option is not available. If, however, you open the share settings of the album, then click directly on the URL, that will launch the album into a different browser window and you will be in the same "viewing mode" that the other users would see, and in that mode the "Download All" option should be available.