How Can I Make A Script That Gives A Players A Force Field While They Are In The Lobby?

game.Players.PlayerAdded:connect(function(player)
    player.CharacterAdded:connect(function(character)
        Instance.new("ForceField",character)
    end)
end)

If this isn't what you asked for, too bad, this is not a request site and you didn't attempt to script it. Something I will tell you is, if your game is a game like, Mad Games, make it so when the player is teleported to the map, make the script remove the forcefield.

for i, v in pairs (player:GetChildren()) do
if v:IsA("ForceField") then
v:Destroy()
end

You should take an attempt at scripting this first, then allow us to give you some assistance with your code. Although, I will tell you that to do what you are asking you are going to need to have some way of checking what "Zone" the player is in and have it check until the player is out of the zone.