Download the plugin file and unpack the content to the /ext folder.
The structure under /ext/komfortkasse should look like this now:
Open the following url in a browser: http://<your-shop>/ext/komfortkasse/install.php
The Auto Installer will start. If you see a blank page only, edit the install.php file and uncomment lines 13 and 14 in order so see any error messages that occur.
After finishing the installer, open your admin panel and navigate to the Komfortkasse settings (or just follow the link supplied by the installer).
Make sure that "Export orders" and "Update orders" are set to True.
Choose the relevant payment type codes. Only order with these payment type codes will be exported to Komfortkasse. You can enter multiple values seperated by comma. Depending on the Bank Transfer module(s) you use, this could be "eustandardtransfer" and/or "moneyorder".
Choose the relevant statuses for open (unpaid) orders. Only orders with these status codes will be exported to Komfortkasse. You can enter multiple values seperated by comma. Typically, this will be 1 (open).
Choose the status that an order will be set to if the payment is received. Typically, this will be a custom "payment received" state or the standard "processing" state.
Choose the status that an order will be set to if the order has been cancelled. Typically, this will be your custom "cancelled" state.
Do not change the other options (encryption, access code, secret keys). These values will be automatically filled in when you connect your shop with Komfortkasse.
Next Step: register and connect your shop