Does it say something like "This application was downloaded from the internet?", and only has an OK/cancel button?
If so, right-click the file in your downloads and click on open, then it should allow you to run it.
If that is not the issue, then you can also manually download the addons from https://www.esoui.com/ and extract them into your User/Documents/Elder Scrolls Online/live/Addons folder.
Did you try Java version from Minion's site? It's standalone .jar file that doesn't require any installation so it may work in such restricted environment.
Move the folder that is inside the zip into your User/Documents/Elder Scrolls Online/live/Addons folder
(the slashes are the file path, so Inside of your documents folder, there's an eso folder, inside of that there's a live folder etc)
Start the game or if you already have the game open, do /reloadui
OK, you can laugh now. I am a 77 yo who knows just enough to be dangerous to me and the machine. I am no Tecki. I have downloaded addons as shown above. However, as I have an iMac, the downlads came in as files, not zip files. Any suggestions? Thanks.
If you download the addons manually they should be a zip file too, if you download them from www.esoui.com?
Not sure what files did download for you? What is their extension? MAybe they are a zip Archive but just not showing the extension?
Are you able to open the files and see the contents?
e.g. if there is a file called Dustman_v12.zip (could show as Dustman_v12 for you) and you open it, it contents will be a folder
called "Dustman" and in there is a "Dustman.txt", "Dustman.lua" and other files and folders.
The complete "Dustman" folder with it's contents need to be extracted to your live/AddOns folder then. Not sure where MAC stores it though :-(
The internet says this about the MAC's addons folder for ESO:
~/Documents/Elder Scrolls Online/live/AddOns/
So in the end it must be
~/Documents/Elder Scrolls Online/live/AddOns/DustMan then containing the Dustman.txt, Dustman.lua and the other files and folders of the addon.
After login, or if you were logged in to the game as you updated the addons: Logout and log back in and you should be able to see them in your ingame AddOn Manager.