Please don't test your biller setup with Plug'n Pay's test account—it won't work correctly.
Setting up on Plug'n Pay's Website
While registering with Plug'n Pay, make sure to take down the Username (or publisher-name), Password (or publisher-password), Domain, Plan ID (for each site you set up), and Purchase ID (for each join option you set up) that are provided to you by your biller. This information will be necessary for setting up Plug'n Pay in NATS4.
Setting up Plug'n Pay in NATS
When prompted, fill in the Username, Password, and Domain that were provided to you by Plug'n Pay under the "Account Info" section. The current default Plug'n Pay Domain is pay1.plugnpay.com. If you were not provided with this information, please contact your biller to receive it.
Next, go to the Sites Admin, create or edit a tour, and scroll down to the "Biller Details" section. Enter your PLUGNPAY E-Mail and Expire File Path in the provided fields; the E-mail field specifies where customer order confirmation e-mails will appear to come from, and the Expire File Path field specifies where Plug'n Pay will store your list of active usernames and passwords.
Once you have done this, scroll down to the section labeled "Join Options for this Tour" and click the "Edit Option Details for this tour" icon that corresponds to the join option you wish to use. In the "Biller Codes" section on the next page, enter your Plug'n Pay Plan ID and Purchase ID into the "PLUGNPAY" fields.