Spotify on Apple Watch, No iPhone

Hi all - I have my son using an Apple Watch SE2 with cellular as his only device. He got AirPods and wants to play music. Other sites indicated listening to Spotify on an Apple Watch was possible, but when I tried to download the app on his watch it says “Requires iPhone” in the App Store. My phone is the device which his watch was set up with and I have the app on both my phone and my own Apple Watch, and each work fine. Any ideas how he can use Spotify?