How could my resell client login to his hosting control panel?

Reseller Plan > Control panel V5
Where to login to resell Account?

The resell customers will only have access to a private hosting control panel. To access the private hosting control panel by URL:

Note: If you had customized your resell control panel login url, resell client can also use it as the portal to login. For more details, please click here

What is the login info?

The login info is created when you are creating a new resell account through reseller control plan.