Windows 7 is not available for Mac but there are some alternatives that runs on macOS with similar functionality. The best Mac alternative is macOS, which is free. If that doesn't suit you, our users have ranked more than 100 alternatives to Windows 7 and eight of them are available for Mac so hopefully you can find a suitable replacement. Other interesting Mac alternatives to Windows 7 are HoloISO, MINIX 3, illumos and PureDarwin.
A Unix-based OS for Mac with seamlessly integration with Apple’s ecosystem, offering an intuitive UI, productivity tools like Finder, Spotlight, and Automator, built-in apps like Safari and Photos, Continuity for cross-device functionality, and security features including FileVault and Gatekeeper.
MINIX is a POSIX-compliant Unix-like operating system based on a tiny microkernel running in kernel mode with the rest of the operating system running as a number of isolated, protected, processes in user mode.
illumos is a free and open-source Unix operating system. It derives from OpenSolaris, which in turn derives from SVR4 UNIX and Berkeley Software Distribution (BSD). illumos comprises a kernel, device drivers, system libraries, and utility software for system administration.
Darwin is the Open Source operating system from Apple that forms the basis for Mac OS X, and PureDarwin is a community project to make Darwin more usable (some people think of it as the informal successor to OpenDarwin.
GNU-Darwin aims to be the most free software distribution. Our mission is two-fold: Focus on projects that leverage our unique combination of Darwin and GNU, and help users to enjoy the benefits of software freedom.
United States
Netherlands
EU
In my opinion if you're to this day using Windows 7 (or even older) you have no business with macOS. Trying out Linux (like Mint, Manjaro, MX or Fedora) is a much better idea and investment (for your knowledge and skills, money and privacy).