Mavericks OS download

Your mac can install Mac OS X Yosemite 10.10 or El Capitan 10.11.

How to upgrade to OS X Yosemite – Apple Support

How to upgrade to OS X El Capitan – Apple Support

Here are the instructions for Yosemite, the instructions for El Capitan are the same just replace Yosemite

with El Capitan if you want to install El Capitan.

Go to Section 4 and click on Download OS X Yosemite.

This downloads InstallMacOSX.dmg to your Downloads folder.

The next section can only be done on a mac that is capable of running Yosemite,

a mac that came preinstalled with an OS later than Yosemite will refuse to do the next bit.

When downloaded open to InstallMacOSX.pkg, double-click on

that and an installation window will open, this does not install Yosemite

but converts the InstallMacOSX.pkg to the Install OS X Yosemite.app which 

you will find in your Applications folder.

 (If the installation window asks which disk you want to install to, you must pick 

the disk that you are booted to at the time. Not any internal or external disk that 

you want to eventually install Yosemite on, that is for later.)

To start the installation of Yosemite double click on the Install OS X Yosemite.app.

The copy of the install app self deletes after installing Yosemite, so make sure you keep a copy of the InstallMacOSX.dmg

if you need it in future, or you could just make a copy of the Install OS X Yosemite.app prior to installing and moving it to

an external drive for safe keeping. It is also possible to create a bootable USB installer disk using the Install OS X Yosemite.app

in the Applications folder and the createinstallmedia command in the Terminal app. 

Read the instructions here,

How to create a bootable installer for macOS – Apple Support

sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ OS\ X\ Yosemite.app

One option is to boot a machine with 10.8 or 10.7 and download mavericks from the App Store.

This is what I had to do for one of my old machines.

Check this page to see if it helps:

https://www.macworld.co.uk/how-to/download-old-os-x-3629363/#toc-3629363-5

Apple no longer provides the full install version of Mac OS X Mavericks for download.