Play soundboard sound
The Play soundboard sound block plays a soundboard sound in a voice channel, the same way members play one from the soundboard. Discord plays it for everyone in the channel, so it needs no uploaded audio and no Premium, unlike Play audio.
Your app has to be in the voice channel already, so use Join voice channel first. It can't play sounds while it's muted or deafened, so leave Mute Self and Deafen Self off when joining. Leave the Voice Channel empty to use the channel the flow runs in, like a command used in a voice channel's chat.
The Sound is the ID of a soundboard sound of the server, or of one of Discord's default sounds. To play a sound of another server your app is in, also set Sound From Server to that server's ID. Your app then also needs the Use External Sounds permission. To find the IDs of a server's sounds, send a GET /guilds/{guild_id}/soundboard-sounds request with the Discord API Request block, and GET /soundboard-default-sounds for the default sounds.
Your app needs the Speak and Use Soundboard permissions in the voice channel.