I also have the same error. It seems like the Softaculous cPanel instance IP, at scriptinstall.rocks, is taken down maybe due to DDoS or maintenance issues. In the meanwhile you could install WordPress with the steps on the official WordPress support website, but for the database you need to create it from the “MySQL Databases” section of the Control Panel and use the database details from that page, but not the username and the password (those can be found on your hosting account page of the Client Area, then scrolling down to Account Details and clicking on Show/Hide to show the password).