Ah, I see. It "writes some files" then asks you to update.
I wonder if they do the courtesy of using our shared jailbreak certificate?
Sounds like a frankenstein remix of the MR jailbreak, calibre, and the Kindle Collections plugin with barsanuphe's librariansync extension.
Perhaps they don't use calibre at all, although many ebook applications do. They seem to be duplicating some functionality, though.
Their About page does not impress.