Order cannot be paid for

Hi guys,

I got a problem here –

Current woocommerce settings is to ” Allow customers to log into an existing account during checkout”

However after logging in, customer is redirected to a blank page and is presented with the following message “This order cannot be paid for. Please contact us if you need assistance.

Screenshots:
https://i.imgur.com/3cQEJTf.png

To replicate the issue:
1) In incognito mode, navigate to senaglobal.co
2) Add Pre-Cleanse 50ML to the cart
3) Checkout and fill in the details. Use Malaysia as a country of choice.
4) Pay with Billplz -> When clicked, this will re-direct you to the login page
5) Login with the following sample creds -> Provided in the site access info
6) U will be presented with the order error.