vCenter 7.0 and 8.0 do not support managing ESXi hosts older than 7.0. You must use the built-in Host Client or a dedicated vCenter 6.7 appliance.
Elias ejected the USB drive and hit Enter to reboot. download vmware vsphere hypervisor -esxi- 6.7
DCUI (Direct Console User Interface)
Running ESXi 6.7 in 2024 and beyond carries significant risks: vCenter 7
When it was current, ESXi 6.7 introduced several significant improvements over version 6.5: download vmware vsphere hypervisor -esxi- 6.7