Configuration is very simple - just enter your Paymate user ID and choose your preferred currency.
When submitting an order, depending on the response from Paymate the ecommerce order will either be marked as "Pending" or "Authorized". If payment is declined, then the user is redirected back to the payment method selection page on your website.
Paymate does not offer test accounts or a sandbox environment. If you need to test, the official advice is to make a low value purchase, and then contact customer services to obtain a refund.