You don’t have to install anything if you want to install a different operating system on your Mac.
However, the latest version of macOS can be installed by simply installing the latest Mac OS version.
If you want, you can install Ubuntu in that same way.
There’s no need to install it from scratch, of course, just download and install the latest macOS version from Apple’s website.
Just remember to restart your Mac before starting to install the operating system.
To make things easier, you may want to read the Mac OS FAQ first.
Follow the instructions to install Mac OS 11.10 Yosemite on your MacBook Pro.
If that doesn’t work for you, try this guide instead.
It’s a little different, but you should be able to get it to work.
Follow this guide to install macOS on a Mac Pro.
You can also use the instructions on this page to install another operating system, such as Linux.
If Ubuntu doesn’t install, you’ll have to try the Ubuntu Linux CD image or install it manually.
Ubuntu Linux is a free distribution that’s used for the Mac operating system that has been developed by Canonical, a company that was acquired by Microsoft for $970 million.
For a more technical look at the Ubuntu project, read our guide to installing Ubuntu on Macs.