VirtualBox is a free program that allows you to install and run a different operating system within another OS. This emulator by Microsoft aims to emulate Windows OS on your Mac giveing.
Your Mac also needs at least 4GB of memory and 12.5GB of available storage space, or up to 18.5GB of storage space when upgrading from OS X Yosemite or earlier. If you're using one of these computers with OS X Mavericks or later, you can install macOS Catalina.