How to get userId from player name?

I am working on a game lobby that will allow player to join into a game if they search for a friends player name, but I have not been able to find any way to get the userId from the player's name. The two players will probably not be in the same lobby either.

This is what I have so far

local teleService = game:GetService("TeleportService")

module.GetPlayerLocation = function(playerName)
	local userId 
	--convert player's name (playerName) into their userId
	local success, errorMsg, placeId, instanceId = teleService:GetPlayerPlaceInstanceAsync(userId)
	if (success) then
		return placeId, instanceId
	else
		return false
	end
end