If you are based in the Republic of Ireland, then i assume you would need to go to the ROI webpage (what is the nowtv web address shown on your television screen where it asks you to use the activation code) ?
Also, i am not familiar with the ROI website and if the nowtv stick is available to buy in ROI.
So i am assuming you have bought the stick within the ROI and not from the UK.
I bought the nowtv passes on web sit in irl.
i bought the nowtv stick on amazon uk...
and yess all is here in Irl same as uk .
I currently watch now tv on my computer/ you can watch now tv now any were in europe .
i wil wait for chat and see if i can get sorted
I might be wrong but i think that the nowtv boxes and sticks are Geo blocked to the region you bought them from.
Maybe that's the issue where you are having difficulty activating a code from a UK sourced stick in the ROI.
Your best bet is to speak to live chat ROI, but make sure you tell them you bought the stick from Amazon UK.