Below are the steps to get an ARM64 version of Ubuntu running in the QEMU emulator on Windows 10.
Install for Windows from https://qemu.weilnetz.de/w64/ (I used qemu-w64-setup-20181211.exe)
Put C:\Program Files\qemu on your PATH, and run the below to check it's working (which will list out
the CPUs the AArch64 emulator can emulate):
qemu-system-aarch64 -M virt -cpu help