OpenCore Question: Where does it download the macOS installer files?

My opencore always stops unpacking the downloaded macOS installer.

Therefore, I would like to unpack it by hand.

But I can't find the downloaded file.

With my slow 6mbit DSL it's a pain to reload Sonomas big-package more than once. So I hope the downloaded installer is somewhere on my system.

Can anyone tell me where to look for that 13 GB file?