The speaker UNpreparedness room is on the left side of the talks floor of the castle, accessible from the Talks Lobby.
You can talk with Tangle Coalbox, Morcel Nougat, and Release the Snacken.
The challenge for Snowball Fight is here.
Just south of the doorway is the elevator 1.5 button.
After you activate the vending machine as part of the Speaker UNprep challenge, after you talking with Release the Snacken a few times he will give you the portals.
An overview of all people, places, and events can be learned in the Introduction.