Orlo,
No, you can but you don't need a Mac machine to generate iOS installation files from Cloud Make, you can also do this from AppStudio Desktop in Windows and Linux as well because AppStudio is a cross-platform native app development platform.
Do you have the proper certificate for the iOS Cloud Make? You can set this up in Settings > Platforms > iOS.
Can you give us more information about the app and the iOS device? I have just tried this with a proper certificate using our MapViewer template in iPhone 8 iOS version 13.2, and it works fine.
Thank you,
Erwin