You need a streamer to hook to your internet/router and a DAC to be able to feed your NAD. The easiest solution, at least initially, would be to get a good combo streamer/DAC like this…
https://jaguaraudio.com/product/pulsemini-streaming-network-player-by-innuos/
This offers very good streaming performance, and you can upgrade to a better DAC later for better performance. And, very importantly, it comes with the Innuos Sense app that gets top marks for both sound quality and usability, and their customer support is also top notch should you ever need it. This is what I’d do if I was you and was just getting started and wanted a minimum of hassle. Also, do a free trial of both Qobuz and Tidal and see which one works best for your needs and music tastes. Hope this helps, and best of luck.