There are two ways to access the hosting control panel.
Login via the billing section
After choosing and ordering a hosting plan, go to the service management page at https://ramendomains.name/clientarea.php?action=services. Click on the relevant hosting account, and then in the left-hand menu, click "Login to Plesk" — the login will proceed automatically.
Login using credentials from the activation email
After ordering hosting, you will receive an email with a link to the control panel, as well as your username and password. Use these to log in.
These credentials also work for FTP access to the server!