According to the documentation:
Go to the ArcBox-Client machine via RDP and from Hyper-V manager right-click on the ArcBox-Win2K22 VM and click "Connect" (Administrator default password is ArcDemo123!!). Then start Windows Powershell ISE in the ArcBox-Win2K22 VM and copy the content of the onboarding script in the Script Pane.
However, the password created by the PS script is JS123!!