I had the same problem and solved it through Live Chat. I had tried using my mobile phone with wi-fi and then three different browsers. Each time I got the same "oops" message. I was advised to try my phone without the wifi and it worked straight away and asked for the code.
Maybe the stick is faulty take it back to where you bought it from i had this issue
had the same problem while trying to activate the tv code on my phone using chrome browser so I went on my laptop and used edge browser instead and it worked no problem.
same problem activating Now tv sick
Following the given connection procedure, resulting in NOW TV logo only then blank blue screen. No further instruction or connection to my internet.
Like other members my smart stick was fin for a week and whilst it starts and takes me through to my TV as soon as I choose a channel the 'Oops something is wrong, cannot download video comes up. I have re-bootesd several times but stick gets quite warm but is still faulty