For account creation to work successfully with DirectAdmin, you must have your packages setup in your DirectAdmin control panel. Here is how to setup hosting products in WHMCS to work with your DirectAdmin server.
Server Modules
cPanel/WHM - DirectAdmin - Plesk - Helm 3 - Helm 4 - Ensim - InterWorx - DotNetPanel
Lxadmin - Virtualmin Pro - XPanel - HyperVM - FluidVM - SolusVM - Cloudmin - WHMSonic
CentovaCast - SCPanel - CastControl - GameCP - TCAdmin - Reseller Central - Auto Release
Registrar Modules
Enom - ResellerClub - Nominet - OpenSRS - ResellOne - OnlineNIC - PlanetDomain
DistributeIT - TPPInternet - RegisterFly - Stargate - Namecheap - NetEarthOne
12Register - Registercom - DotDNS - WebNIC - Dot.TK - HexoNet - Realtime Register
Fraud Modules
MaxMind - VariLogiX FraudCall - Telesign
Selected Gateway Modules
Payflow Pro - Authorize.net - BluePay - Quantum Gateway - eWay - eProcessingNetwork
InternetSecure - LinkPoint - SecPay - ProtX - PSIGate - WorldPay Invisible - NaviGate
Merchant Partners - PayOffline - Offline Credit Card - PayPal - ChronoPay - 2CheckOut - Google CheckOut
WorldPay - E-Gold - Gate2Shop - F2B - PagSeguro - NoChex - AlertPay - ProtX VPS Form - Paymex
CashU - Liberty Reserve - StormPay - Paymate AU and NZ - Payson - BRPay - Boleto - MoneyBookers
PayOffline - Mail In Payment - Bank Transfer - USA ePay - Pay Junction - PayPal Website Payments Pro