This is the most common error when installing older versions of OS X. It occurs because Apple's original security certificates for the installer package expired after February 2016.
Apple has largely removed OS X Mavericks from its active servers.
While Apple no longer offers Mavericks on the Mac App Store for new users, you still have some options for obtaining a .
Open the on an older Mac running macOS High Sierra or earlier. Click on the Purchases tab at the top of the window. Scroll through your history to find OS X Mavericks .
Before downloading, ensure your hardware is compatible with OS X Mavericks. Supported Mac Models : Mid-2007 or newer
Are you looking to install on a virtual machine or onto a physical Mac ? OS X Mavericks | Specs, reviews and EoL info - InvGate