You’ll need to plan out your domain before you begin. In my case, I already had my network configured to use 192.168.254.x. My Fiber router serves as my default gateway as well as my DHCP server and primary DNS server for my local network. My wireless access points, primary workstation, and printer are already set up for static IP addresses. I have already set aside a subnet of addresses for static servers. I also already own a domain name (toyboxcreations.net). Having all this set up before trying to install my domain controller help by saving time.
Shannon glosses over the local AD part, but once that’s set up, shows how to tie it in with Azure Active Directory.