apple says macos sierra download cannot be installed on my computer
Apple says Mac OS Sierra, Sierra High and Mojave downloads cannot be installed on my computer, though my early 2009 Mac does meet the General Requirements.
Currently I have Mac OS El Capitan.
Example of Apple message when trying to download Mojave -
"This version of macOS 10.14.6 cannot be installed on this computer."
How else can I get one of these upgraded Mac OS downloads?