This could happen for various reasons.
One of the known reasons is that this happens because DHCP provides both IPv4 & IPv6 information and SCI is not able to resolve IPv6 information.
As mentioned in the install guide, SCI does not support IPv6. If that doesn't fix the problem, please SSH into SCI VM and copy out logs from cluster manager using the below command and send allout.txt to Support.
sudo docker logs rsa-cluster-manager-setup > allout.txt 2>&1