Deploying a brand new vCSA 6.7 appliance results in the following error during the second stage of the deployment.
This problem is almost always caused by DNS resolution. Once you create the appropriate A and PTR record for your appliance on a LOCAL DNS server, you should be to successfully complete the deployment. Local DNS resolution is required, you cannot use a public DNS server while installing vCenter. For example, 18.104.22.168 will not work.
Since you have already completed Stage 1 of the deployment, you can login to the appliance via SSH and update the DNS settings. This will only work if you chose to enable SSH during Stage 2 of the deployment.
SSH to the appliance and run "/opt/vmware/share/vami/vami_config_net" (without quotes). Choose option 4 to update DNS settings and option 3 to update the hostname (if necessary). The deployment wizard states that a hostname is optional, but it is actually required. I have never had a successful deployment without specifying the hostname.
You can then verify the DNS settings have been updated in the resolve.conf: