late 2009 imac reinstall el capitan on clean drive. Used Transmac on pc to create Bootable USB installer. put the usb drive in imac booted recovery mode, selected USB drive. All goes well up to ;sign into app store; after sign in i get Error 403 forbidden.
iMac, OS X 10.11
Used Transmac on pc ...
That won't work. To learn how to create a "bootable USB installer" please read Create a bootable installer for macOS - Apple Support.
You can also use the original gray OS X Restoration DVD which shipped with the iMac from the factory.
Once you get OS X 10.6.8 installed, then you can copy the macOS 10.11 DMG file to this old iMac so you can upgrade to El Capitan. After that you can upgrade to macOS 10.13 High Sierra.
late 2009 imac reinstall el capitan on clean drive.
