
That said, in hindsight, the same trick could have worked with Maverick too using the recovery partition. Hence straight to El Capitan which supports the security code (via the login ). PS: The above work for me on a Macbook Pro 2009 and Maverick but I could not reinstall Maverick due to an itunes login to old and incompatible with the security code that Apple uses now.

Reboot and redo the process with Safari first then the Install. For a quick start please read the readme file on the disk image. If youve ever wondered where all your disk space has gone, Disk Inventory X will help you to answer this question. It shows the sizes of files and folders in a special graphical way called 'treemaps'.
DISK UTILITY OS X EL CAPITAN DOWNLOAD FOR MAC OS
Don't try to install and see the "temporary unavailable" bug and then try the Help/Safari trick. Disk Inventory X is a disk usage utility for Mac OS X.
DISK UTILITY OS X EL CAPITAN DOWNLOAD MAC OS X
Click on the "install OS X" item, follow instructions and it should NOT ask you for itunes anymore and therefore not timeout with "This item is temporarily unavailable. To create a bootable Mac drive you need any disk with Mac OS X 10.11.0 El Capitan or newer (10.12 Sierra, 10.13 High Sierra, 10.14 Mojave, 10.15 Catalina) either running as your main system, or just being installed on a drive that's connected to your Mac at the moment. (You might need to go the top menu to exit Safari). Then type, log in with your itunes credentials. Select the "Get HELP Online" item which will open Safari. Try another USB port and wait 10 sec again. If it does not detect it after 10 sec and you only see your hard-drive. Start your Mac, press immediately OPTION (aka ALT) Select the Orange icon (aka a USB stick) labelled El Capitan. Plug-in your USB key on a turned-off computer. Try another USB port and wait 10 sec again. I created a USB disk with a bootable El Capitan as per this documentation.

