While creating the sub domain in the cpanel you may get error as below:
"You do not have permission to create subdomains of the server's hostname"
Please follow the below steps to solve this issue:
Step 1: Login to the WHM >> go to Tweak Settings
Step 2: Search for the option "Allow users to park subdomains of the server’s hostname."
Step 3: Enable the same and save the changes.
Step 4: Now try to create the sub domain in the cPanel.