[iPay88] What is the «Staging URL»?

Extensions iPay88
,
1

iPay88 support says:

Kindly fill up below information:
<…>
Request URL/ Staging URL/ Test URL

But the «Staging URL» termis absent on the iPay88 website:

So, what is it?

2

I have got an answer from iPay88:

the url of your website that you wish to integrate with ipay88.