I’ve not used Epubor Ultimate. It sounds like it’s a more straightforward way to go.
You can also try the instructions here:
This is how to use calibre to do it. If you have a kindle it’s also a little easier. You just need calibre and the plugin. Then you can “download for usb” from content section in audible. Just open in calibre and then convert to mobi. You’ll have to enter your kindle credentials somewhere in Calibre. I don’t remember off the top of my head. BTW, on newly published Kindle books they are using a new DRM. I don’t know if any of the above ideas work yet on those yet. I’ve not come across that issue myself yet.