Yes, that’s what he’s saying. Sonos doesn’t allow the Sonos library to be on any mobile device, be it an iPad or an iPhone, or the Android equivalents, as they can easily leave the network at any time, leaving any other users bereft of music.
Sonos does allow you to play from music stored on PC/Mac, or even an NAS. Or, if you have an Apple Music subscription, from the Apple Music servers.
Apple closed the loophole many years ago that several companies were using to allow playback “from this device”, so at this point, if you’re playing music stored on an mobile device, you must use, as @John B suggests, AirPlay 2 (for those speakers that have it) or Bluetooth, by placing a Bluetooth receiver in the line in on your PLAY:5 gen 1.