If I'm reading the manual correctly (and I admit to just skimming it), it would appear the internet connection is only necessary to generate a secure file. You can download the file from the device and it's stored locally, but by connecting the FlywithCE server it then generates a secure file for OLC flights (and I presume, Silver and Gold badges). You don't have to connect to download the file and the device itself doesn't connect to the internet.