Expected identifier when parsing expression, got '>='. How do I fix?

local config = script.Parent.Configuration

game.Players.PlayerAdded:Connect(function(p)
    p.Chatted:Connect(function(chat)
        if chat ==";b" then
            GetRankInGroup(config.GroupId.Value) >= config.RankId.Value then
                p.Character.HumanoidRootPart.CFrame = CFrame.new(workspace.teleport.Position)
        end
    end)
end)

You had some issues with your ends and forgot to put an if before GetRankInGroup

local config = script.Parent.Configuration

game.Players.PlayerAdded:Connect(function(p)
    p.Chatted:Connect(function(chat)
        if chat ==";b" then
            if p:GetRankInGroup(config.GroupId.Value) >= config.RankId.Value then
                p.Character.HumanoidRootPart.CFrame = CFrame.new(workspace.teleport.Position)
            end
        end
    end)
end)

thats because GetRankInGroup is a function that checks the players in the group

if i were you change that like this

01	local config = script.Parent.Configuration
02	 
03	game.Players.PlayerAdded:Connect(function(p)
04	    p.Chatted:Connect(function(chat)
05	        if chat ==";b" then
06	           p: GetRankInGroup(config.GroupId.Value) >= config.RankId.Value then
07	                p.Character.HumanoidRootPart.CFrame = 			 
                        CFrame.new(workspace.teleport.Position)
else

  08                     -- do something here lol
09        end
10	    end)
11	end)