Bootcamp will not let me install anything besides window 10 and I cannot find the instructions to create a bootable windows 7 usb using catalina anywhere online.
Find out how to install Windows 10 on your Mac with Boot Camp.
support.apple.com
' Install Windows using Boot Camp for macOS High Sierra and earlier
In macOS High Sierra and earlier, you can install Windows 10, Windows 8.1, and Windows 7 using Boot Camp Assistant on supported Mac models. '