Is there a way I can get my Books from the App to export to Calibre so I can sync them to my wife's Kindle? I can find the .epub files, but am having difficulty getting them into the Calibre app on her Mac, or I'd even go directly to the Kindle if possible. The email to Kindle feature returns an error as well. I was able to do this seamlessly years ago, but I'm having trouble locating info on getting it done now. I assume things have changed in the last few years? Thanks!