ServerShield by Cloudflare not connecting

My ISP has an option for ServerShield by Cloudflare via the Plesk admin interface. I have a Cloudflare account, but when I add the login details it states there is a connection error: Error: Invalid host key. Even though I add my correct Cloudflare credentials and also as it doesn’t try to even create an account when it doesn’t recognise my credentials, even though it says it will in the interface,
Any help?

Thanks in advance