Hi @Eddie_Hsu,
I have an Ambeo Soundbar, and it plays from my core and Roon remote without issue. My core is Windows 11 and the remotes are an iPhone 13 Pro Max/iPad Pro. First, have you done the steps in this post [Set device permissions in the Home app.] ?
When I installed the soundbar, Roon created the “Default Room…” AirPlay device in the image below. To see if adding it as an accessory in IOS as suggested by @noris, I tried it and it worked; it created the second device labeled “Ambeo” in the image below.
Connection infol:
The soundbar is the primary speaker for my AppleTV. I have an HDMI cable running from the AppleTV to the soundbar, then back to my TV. The soundbar is connected to WiFi.
Hope this helps.