Allow Knox Payments (pay with online banking) as a Payment Gateway in WooCommerce..
Install by searching for "Knox Payments Woocommerce" on the WordPress Plugin "Add New" screen
After you do that, activate the plugin in the plugin maintenance page, and navigate to Woocommerce - Settings - Checkout -> Knox.
Upon arrival at that page, fill out the API Key, API Password, the custom text you want to appear on the button at checkout, and the invoice detail to describe how this should show up on bank statements. Do not touch the other variables unless instructed by someone at Knox Payments in order to enable recurring payments.