Web Host Manager (WHM) for configuration. E.g., in WHM you can add user accounts, databases, and configure resources. It uses port 2087 and can be accessed by the URL https://mycpanel.com:2087;
cPanel for virtual hosting management. E.g. in cPanel you can manage domain names, set up FTP access, or a mail server. It uses port 2083 and can be accessed by the URL https://mycpanel.com:2083.
One service in BILLmanager is associated with one user in cPanel. You can create cPanel user accounts only in WHM. That's why you need to set up the integration with WHM using the superuser permissions.
Before you create a tariff plan, create an appropriate resource package in WHM. If the tariff plan contains a non-existing package, the service won't be activated.