Installing El Capitan from OS X 10.6.8
I have this old iMac - it can run up to El Capitan and is currently running Snow Leopard 10.6.8.
From the appstore I can now only get Sierra.
Installing with an El Capitan DMG I get the error "This copy of the Install OS X El Capitan application can't be verified. It may have been corrupted or tampered with during downloading."
The DMG has been verified and is all good.
Any ideas please?
Is this a good question?