Podcini 6 has a different applicationId of Podcini.R, so it installs in parallel with earlier versions of Podcini on any device.
Once installed, it starts afresh, without any podcasts subscribed.

Podcini 6 has overhauled database and routines completely, the iron-age celebrity SQLite is replaced with the modern object-based Realm.
While Podcini 6 can export/import the Realm DB, the SQLite DB from version 5 and below can not be imported.

To update it with your current subscriptions, listening progress, episodes marked favorite, and app preferences,
the following can be imported to it from Settings -> Import/Export:

* preferences files
* OPML file
* json file of episodes progress

An OPML file should be imported before importing episodes progress, but you can always re-do any of the above

These files can be best exported in version 5.5.3 in Settings -> Import/Export

Then your subscriptions, listening progress, favorites, and app preferences will be updated.

Unfortunately, media files will need to be separately downloaded.

* Note you can also export the progress from version 5.5.2 if you don't have 5.5.3, the difference is only that 5.5.3 includes the info about how far out an episode has been played, which can be useful when looking at statistics. Without that info, you can get similar (albeit not exactly the same) results by "Include marked played" in the filter of the statistics view.

* Note also, if you have played some episodes using Podcini 6, importing progress from version 5 will not overwrite your progress new episodes in version 6.