How do I get resettimer to sync with TextLabel?

I have a chest that rewards money and resets every 20 minutes and I would like a timer above (I already have a BillboardGui with a TextLabel in it and script in the TextLabel) I'm not sure how to have the respawn timer sync to the TextLabel when the respawn timer starts.

Wait, are you just asking for the value of the respawn timer to go to the text label? If so, make a loop, search up how to do that and do something as simple as

local Timer = 20
Loop here
Timer = Timer - 1
script.Parent.Text = Timer
Wait(1)
end

Add an if statement for as long as it isnt equal to 0 repeat. if its equal to 0, Timer = 20 or put it on hold however you want to.

local function toMS(s)
	return ("%i:%.2i"):format(s/60%60,s%60)
end

local minutes = 20
local seconds = minutes * 60
local textlabel = --path to billboard textlabel


while task.wait(1) do
	textlabel.Text = toMS(seconds)
	seconds -= 1
	if seconds = 0 then
		seconds = minutes * 60
		print("Finished!")
		task.wait(5)
	end
end

What the function does is it returns a formatted version, so 20 mins will be 20:00 and 5 mins will be 5:00