We are using the Joomla Payment API (https://github.com/techjoomla/joomla-payments - Thanks to Techjoomla!) for payment management, which comes with a Joomla plugin for every payment method. In the Joomla backend go to Extensions -> Plugin Manager and filter the type to "payment". Now you can see all available Matukio payment plugins, just click on one to configure it. Some plugins, like banktransfer, have some additional configuration options in the settings.