Your humidifier posted appears to belong to the Legacy series machine which is the older version. If this is true then you also would need a smart card reader to transfer the card data to the computer software,
So please verify exactly which machine you are using. It makes a difference with which software you need and if you need the card reader or not.
I don't know of anywhere on the internet to buy the software as a download. Might find it free from some file sharing places but those scare me. Would be moot point if you need the card reader and don't have it.