Bootcamp on MacBook Pro, 2017 only supports Win10 installation

Run Windows on Intel Macs

There are presently several alternatives for running Windows on Intel Macs. Here is a list of the primary options in the market place.

1. Apple Boot Camp software. Boot Camp enables you to boot the computer into OS X or Windows. (Free because it comes with OS X. You must own a legitimate Windows Full Retail Installer.)
2. Parallels Desktop for Mac. Parallels is software virtualization that enables running Windows concurrently with OS X.
3. VM Fusion.VM Fusion is software virtualization that enables running Windows concurrently with OS X.
4. CrossOver. Enables running many Windows applications without having to install Windows. The Windows applications can run concurrently with OS X.
5. VirtualBox. Open Source freeware virtual machine such as VM Fusion and Parallels that was developed by Solaris. (Free because it comes with OS X. You must own a legitimate Windows Full Retail Installer.)
6. Veertu. A new entry from Open Source utilizing native virtualization. It’s a fast and secure way to run VMs on the Mac. Veertu Desktop is supported on Mac models of early/mid-2011 or later running Yosemite 10.10 or later.

Parallels, VM Fusion, VirtualBox, and Veertu can also run other operating systems such as Linux, Unix, OS/2, Solaris, etc. There are performance differences between dual-boot systems and virtualization. The latter tend to be a little slower (not much) and do not provide the video performance of the dual-boot system. A 2015 comparison of Parallels, VM Fusion, and Virtual Box is found at 2015 VM Benchmarks: Parallels 11 vs. Fusion 8 vs. VirtualBox 5. A review of these and other competitors is found in PCMag: The Best Virtualization Software of 2017. Boot Camp is available with Lion and later.

You must also have an internal optical drive for installing Windows. Windows cannot be installed from an external optical drive. Windows must be installed on an internal drive if you use Boot Camp. A license must be purchased for all commercial software and operating system products. Open Source software is free.

Some Boot Camp Articles from Apple Support.

Boot Camp Support.

Boot Camp 5.1: Frequently Asked Questions.

How to Install Windows using Boot Camp.

Boot Camp Control Panel Users Guide.

Use Windows 10 on your Mac with Boot Camp.

Use Windows 8.1 on your Mac with Boot Camp.

Install Windows 7 and earlier on your Mac using Boot Camp.

System Requirements to Install Windows on your Mac using Boot Camp.

This article makes it appear as if you must use Windows 8 or later.

Create an ISO image for Boot Camp from Windows installation media - Apple Support

Windows 7, after all, is now nearly eight years old.

This article tells what Mac computers support what versions of Windows.

System requirements to install Windows on your Mac using Boot Camp - Apple Support

You can only install Win 10 on that model. Downloaded Windows drivers must be installed after Windows is running. The drivers must be downloaded to a USB drive formatted MSDOS (FAT32).