Newbie Help - Linking specific "My App" Build to web address?

I am new to AppGyver and inherited an app from a former employee. I don’t understand the architecture of Apps, Builds and how things are connected.
Within AppGyver in “My Apps” I have a live application I will call ApGyv_Live and a few test apps, such as ApGyv_TEST. An outside process such as Power Automate can initiate the “My Apps” ApGyv_Live application by creating a link to https://MyApp.appgyverapp.com/ (not actual name)

I don’t understand where MyApp.appgyverapp.com got created, and how it links to ApGyv_Live.
I want to do testing and maybe change to point to ApGyv_TEST instead.

Or maybe create MyApp_TEST.appgyverapp.com to connect to ApGyv_TEST.

Can someone point me to how this might have been defined or configured ??

TIA

While on an active app go to Launch → Distribute → Open Build Service.
The Web Build will give you a zip file with the html files and code.

Save the files (not the folder) to a web server/amazon bucket and access the address .

This may help