The article says that there's a web interface (on the open internet) where you can register and login. This interface allows you to download a build of the malware (with your customer ID embedded in the binary, presumably). The malware sends the stolen data to the server, with the customer ID, and it shows up on that customer's dashboard for them to download. The article doesn't say how payment works, but it's a safe bet to say that they take cryptocurrency. It all seems quite seamless, which makes me wonder how many customers they have, and how popular it is to set up shop stealing information with other people's software.