Join to Create voice channels in Discord
One channel hands out the rest. Somebody joins it, gets a room of their own, and the room disappears when they leave.
Walk it yourself
One channel is the whole setup. Press it below and watch the list answer — the room it hands back is yours, and it is gone again the moment you leave.
Nothing here yet - the room does not exist until somebody joins.
The panel that appears is the real one, and every button on it goes somewhere — press one to read what it does. Any of them can be switched off per server, and the set can differ by role, so members get the controls you want them to have and nothing else.
Setting it up
Add the bot and run /setup. Pick the channel that should do the handing out, and that is it.
The step-by-step version is in the setup guide. Afterwards, name the generated channels with placeholders, and if people start waiting for a free room, turn on auto-scaling.