- they tell you, which (version of) “Kindle for PC” resp. “Kindle for Mac” to use,
- actually they even provide you with exactly that version.
- and they tell you to not update your “Kindle for …”
- https://en.wikipedia.org/wiki/Calibre_(software) – software like calibre has to do the kindle2epub task – but calibre will only (?) start on a DRM-free Kindle e-book