Hi, I want to install macOS Catalina on a partition on my computer's hard drive to test and fix some bugs for my Mac app. I can't seem to find a simple way to download the installer. I found a link to the Catalina page on the Mac App Store through some other website, but when I try to download it, I get an error saying "This copy of the macOS Catalina installer application is too old to be opened on this version of macOS".
I've checked the Downloads page from the developer page, and it's not listed there either. What gives? Shouldn't be easier to test Mac apps on older versions?
FWIW I'm trying this on a MacBook Pro 2016.