Installing DNS, DHCP, Active Directory Server Tutorial for your Domain Controller in Virtualbox
You could get the iso files on the official Microsoft Website.
Windows Server 2019:
https://www.microsoft.com/en-US/evalc...
Windows 10:
https://www.microsoft.com/de-de/softw...
Virtualbox:
https://www.virtualbox.org/wiki/Downl...
If you have any questions or suggestions feel free to ask.
Zariatus