I didn't receive any push notification and couldn't complete my order via Smartpay Bank Direct.

When using Smartpay Bank Direct, you need to turn on the push notification of the Smartpay app. You can check this from Account > Notifications on the app.

When you pay via Smartpay Bank Direct, a push notification will immediately be sent, and you’ll be requested to confirm the bank account to use. Please also disable the silent mode.