You need WHMCS database information to setup WHMPress. The information is required ton WHMPress > Sync WHMCS screen.
To fill in the form above, you can find WHMCS database information from WHMCS configuration file configration.php. The file is located in your WHMCS install folder.
Following are the necessary details you require from this file to sync WHMCS to your WordPress site.
Creating Additional Database User:
Although some expert users may choose to create an additional WHMCS database user for this purpose, you can also use existing database information which WHMCS is itself using.