After Broadcom acquired VMware, the Holodeck pages began moving away from core.vmware.com. Some setup information and documentation was unavailable during the transition.
There is some info here:
https://www.vmware.com/resources/resource-center?category[]=Hands-on%20Labs&term[]=Holo
The setup files for holodeck 4.5.2 /5.0 / 5.1 can be downloaded using this form:
Some documentation is still missing from the Broadcom pages, including the lab exercises and instructions for configuring and testing Holodeck.
The available files are enough to deploy VCF and test SDDC functionality or a Supervisor Cluster for Tanzu. After Holodeck is installed, the Aria Easy Installer can add Lifecycle Manager, Identity Manager, and Aria Automation.