Im getting the error No method name passed in __namecall for Object. Whats wrong?

The problem is that you indexed the Clone function, rather than invoking it directly with a method. The normally defaulted self argument was not passed.

In other words, object:Clone(); is the same as object.Clone(object);.

Here's an example of how that works:

local world = {
    Bob = {
        Name = "Bob";
        SayHello = function(self)
            print(self.Name.. " said hello!");
        end
    }
}

world.Bob:SayHello(); --> Bob said hello!

world.Bob.SayHello(); -->attempt to index local 'self' (a nil value)

world.Bob.SayHello(world.Bob); --> Bob said hello!

Also, due to how Roblox handles property listeners, you should set placemap's Parent after configuring the Position Property - read more here.

while restime and wait(10) do
    local placemap = Choose:Clone() --Invoke with ':' !
    placemap.Position = Vector3.new(x, y, z)
    placemap.Parent  = workspace --Parent afterwards !
end