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