During installation, choose "Free Edition." No license file is needed. To unlock additional features (like high availability), you would need a Citrix license server—but for most homelab users, the free edition suffices.
For all other use cases, you should migrate to (an open-source fork of XenServer) or Citrix Hypervisor 8.2 LTS . xenserver 65 iso download top
Older virtual appliances that aren't certified for newer hypervisors. During installation, choose "Free Edition