I need help whit a script for automatic group promotion?

I have an automatic promotion system found but I need an access key to put in does anyone knows what this means

local base = 'http://roblobots.cf'
local http = game:GetService'HttpService'
local group = 4149520
local access_key = ''
local private_key = [[-----BEGIN PRIVATE KEY-----

-----END PRIVATE KEY-----]]
local send = function(action,player,...)
	local parameters = {...}
	return http:PostAsync(base..'/receiver.php',http:JSONEncode({
		action = action,
		group = group,
		player = player or nil,
		access_key = access_key,
		private_key = private_key,
		parameter1 = parameters[1] or nil,
		parameter2 = parameters[2] or nil,
		parameter3 = parameters[3] or nil
	}))
end

local promotePlayer = function(plr)
	send('setrank',nil,2)
end

The key is what access' the API to the website ( I assume ). For example, the key could be this:

local access_key = "QmVnaW4ga2V5"
local private_key = "Something encoded"