I shared an iCloud note with somebody else to work on it together. I sent a link via E-Mail which points to iCloud.com. The other person opens the link, signs into iCloud and then the note is opened in the web app.
While the Apple online help is not very clear about the abilities I expected the note to at least synchronize with the other persons Notes app on macOS (the other person is signed on to iCloud on macOS and notes synchronization is turned on). But not even that. Am I missing something or is it really only possible for the sharing person to edit in the macOS app?
I tried the same with a Numbers spreadsheet which is saved in iCloud, too. Sending the link via iMessage results in the same problem.
Best Answer
Solution: Upgrade to a macOS version which introduced the support to do so. According to the About collaboration for Pages, Numbers, and Keynote article on the Apple Support pages "A Mac with macOS Sierra and Pages 6.3.1, Numbers 4.3.1, or Keynote 7.3.1 or later" is required.
In my case the macOS upgrade from El Capitan to High Sierra provided the desired feature. I simply did not think about the only recently introduced software support.