Dark Horse downloader

Go to your digital library page (gallery view must be selected, so the URL is https://digital.darkhorse.com/library/?display_mode=gallery), and click on the download icon next to the comic book you want to save.

Comics are downloaded as a tar archive that is not compatible with other comic book readers, so you have to convert them using Dark Horse converter (https://github.com/Metalnem/dark-horse-converter) before you can open them in the reader of your choice.