Keyboard shortcut when adding extension to click "Add" and "OK"

When trying to add a Firefox extension the browser asks the user if he would like to add this extension and leaves two options, one of the options is “Add”, I would like to know how I can press this prompt without using my mouse, also the same thing for the “OK” prompt when the extension has been successfully added.
In short - Adding extension without mouse.

Hmmm, the Tab key can get you to the “Add” button without a mouse, but I don’t know how to get to the “OK” prompt afterwards in the popup. I’ll see what I can find out and will post back with any info.

Thank you for your time and effort to answer my question. I would like to say that TAB doesn’t work for me to get into the “Add” prompt.

Are you on a Mac, Win…?

Windows 10…

Solution: Alt+A…