Access to Cirium Sky is based on an allow list. Connections from IP addresses on the allow list are permitted to Cirium Sky.
The connection timeout message suggests that the user is not connecting from an IP address that is on the allow-list for Cirium Sky.
Please check your IP address by typing "What is my IP address?" in Google or going to https://whatismyipaddress.com/
This should tell the user what IP address the AWS Redshift cluster will see when you are connecting.
Please provide us the IP address and we can check if that is one of the allowed IPs.