Huh. I'm using it without problems. Any chance you're using multiple Safari profiles (new feature in Sonoma) and it's not enabled in the profile you have active?
I tried to use Orion, but when I tried to make a new tab group so I could close one of my windows and come back to all its tabs later, Orion made a new /empty/ tab group and closed all the tabs in the window. Worse, none of those tabs were recoverable with Cmd-Shift-T. I had to go back through ~3 days of History reopening things, discovering they weren't the right things, reopening more things…
I went bacb to Safari after I couldn't find an Orion way to make a new tab group without destroying the current window's tabs.
In Safari, could have made bookmarks for these tabs, I guess, but Safari doesn't give me an obvious indication of whether the current tab already has a bookmark. So, my Safari bookmarks sometimes have duplicates because I forgot I'd already made one and didn't burrow though the Bookmarks menu to check. So, Safari tab groups are more useful to me than bookmarks for anything that's part of an unfinished project/idea.
To be clear, I'm not a Kagi support person or anything, and also not arguing that anyone's wrong for saying it's not working for them. Just saying, it is working for some people on Mac and iPhone, so it's not totally borked.
True. I just followed the instructions again and it is working. Apparently I had to allow access on all websites again and change the search engine from DDG to Google for the extension to work.