Can WHMCS customers log in to OnApp directly within WHMCS when using WHMCS OnApp module?
OnApp WHMCS modules
The majority of the OnApp WHMCS modules do not provide OnApp UI access to end users. All billing and VM management is done directly through the WHMCS client area.
The only exception is the users module as it only provides billing through WHMCS and the user has to log into OnApp for VM management.
Please see the docs page for more information about the modules: https://docs.onapp.com/display/WHMCS/WHMCS