The circulation manager can't access manifests, so it can't convert the vendor-specific format to a RWPM the way it does with other vendors. You mobile developers are on your own.

That said, the Overdrive audiobook manifest format is pretty simple and it should be self-explanatory how to find the list of chapter links and download the chapters.

Although simple, the Overdrive audiobook manifest format is in flux and there are a couple of reported issues, notably an apparent lack of chapter titles. Once you start work on this, contact me (Leonard) and I'll check into any remaining issues.

Note that the links in an audiobook manifest are good for one hour. You need to be prepared to refresh a manifest if there's a problem retrieving one of its chapter.