TunesFun Audible Converter is a good replacement for the Audible Download Manager. Since Audible has already migrated to the Audible app and Audible Sync, this is a good time to make the switch. TunesFun Audible Converter can convert those aa/aax files into universal, easy-to-use formats such as MP3, WAV, FLAC, and M4A. Best of all, it can remove the restrictive nature of DRM. It is DRM that hinders you to be able to play these audible files with any music player (such as MP3 players). You won’t be worried about buying non-audible authorized music players now.
https://www.tunesfun.com/audible-converter/audible-download-manager.html