From here:
http://www.centova.com/doc/cast/installation_manual/09_billing_integration/whmcs

says:

16.
This step is optional. If you would like to customize the information shown in the WHMCS client area for Centova Cast accounts, edit the file modules/servers/centovacast/client_area.html under your WHMCS installation directory.

But I don't see anything when logging in as client.
Only the login to panel button and nothing else.

Another one matter also is the:

13.
This step is optional. If you would like to configure the WHMCS welcome email (which is sent to clients when a new Centova Cast account is ordered) to include information about the newly-created Centova Cast account, you may create custom fields for these values and Centova Cast will automatically fill them in with the appropriate values. These can then be used as merge fields in your WHMCS welcome email.

I did all the custom fields, but nothing is showed up when creating account plus
nothing is showed up in welcome email that whmcs sends.

Anyone having any information on that ?

I tried support sending a ticket but waiting 2 days now for it