Along with WHMCS API, WCAP uses WHMPress Helper – a custom extended WHMCS API for extended Ajax functionality. 
WHMPress helper is not part of the WordPress Plugin but was included in the package for easy access. It is now   moved to download link below.

https://whmpress.com/whmpress-downloads/

After downloading the Plugin you will be prompted to generate the license which you will add in your WHMPress helper whmcs module to activate it.
