What nowtv playback device do you own (white box, black box, smart Freeview box, smart stick or smart box 4K)?
Where the pair remote button behind the battery case cover of the voice search style remote is only fitted to the nowtv smart stick and new 4K smart box.
The remote controller supplied with the older boxes don't have the pair button on them because they communicate on IR between the remote and the box.
If you have a nowtv smart stick, then you need the smart voice remote (see link below from Sky accessories shop).
If you have bought a different nowtv replacement remote controller rather than the above, then the other nowtv remotes will not work on the stick because they use IR and not wireless.
More info here about nowtv remote controllers.
Also if you wish, you can control the stick from your smartphone by downloading for free the Roku remote controller App from your phone Apps Store.
If you just bought it, maybe off Amazon for about £8, then it’s the old model.
Without trying to pair it, as you can’t, does it work your NowTV device at all? I believe these can fall back to IR from the old remotes, but I haven’t got one to try.
The new remote is on Amazon for north of £25, which is crazy, as you can get a whole new stick, with smart remote included, for £15.