I think @getrithekd 's guide uses iterative player IDs (from another one of his guides):
I think that you can use a property to represent the current number (and this property increases by 1 each time the Next button in the selector is pressed, resetting when going over the number of players in the game) and use a relay to check if each player’s ID is the same as that. If they are, it sets the Popup header to “Teleport [triggering player’s name]?”
Also I didn’t read the player selector guide beforehand at all so somethings probably not right.
As for teleporting the player, use a relay again but this time have them teleport the chosen player if their ID matches the selected ID.