Earlier quoted context omitted.
Hm, this is a bit strange. It should work fine on Firefox, and a lot of other people on this thread seem to have no issues. Can you share what OS you're on and other extensions you have installed? Feel free to reply via email — my address is dk@getintention.com.
I think I got it sorted. I tried it on 6 different computers/laptops/VMs/Ubuntu/Windows and it never worked. Then I tried Chrome and after I clicked install I was presented with a picture of (I assume) you and a "Continue" button. I had never bothered to click on that before, always going straight to the extension button in the top right corner. However, if you don't press "Continue" it doesn't request the permission…
Thanks for finding this! Will add a check like you suggested.