If you have factory reset your NOW Stick, then unfortunately you need a NOW Smart Voice Remote Controller to initially set up the Stick.
Just be aware the older infra red NOW remote (non voice smart remote) will not work with the Stick.
Once the Stick is setup, you can then use the free Roku Remote App on a smartphone or tablet.
I don't think there is anyway around it 😡.
It also seems the replacement NOW voice smart remote controllers are currently in short supply and places like Amazon & Ebay seem to be asking ridiculous amount of money for an official remote that NOW charge £8 for.