How to Create a cPanel Hosting Product in WHMCS
WHMCS · Self-help guide
After adding the cPanel server, create the hosting product your clients will order. In WHMCS admin, go to System Settings > Products/Services and create or open a product group. Click Create a New Product, choose a hosting product type, enter the product name, and set pricing. Open the Module Settings tab and select the cPanel module. Choose the correct server group and enter the WHM package name exactly as it appears in WHM. Set the automatic setup option carefully, usually after first payment is received. Save the product, then place a test order using a test client before selling it publicly. Confirm the account appears in WHM and the welcome email is correct.