Short answer: most of ‘em. Here is a brief description of the required fields, what they mean, and why it is important.
|Category and Subcategory||Get as close as you can with the vaguely-worded iTunes categories to your podcasts subject matter. It’s in your best interest for discoverability.|
|Explicit/Clean||If you know your podcast will consistently be explicit, mark it as such. You can always override this for each individual episode. Note that if you have explicit content, and it isn’t marked - Apple Podcasts can yank your podcast out of their app. Do not taunt the dragon in its lair.|
Determines how your podcast episodes are ordered.
Episodic presents the content with the most recently published content first.
Whereas Serial, presents your content in a linear format from first episode to last. Recommended for shows you'd like listeners to approach in a certain order.
|Homepage Link||A website URL is required by iTunes. We know most producers have them but in case you don’t, we’re here to help— we can generate a URL for you if you don’t already have a homepage. However, having your own homepage allows you to post extras that may not quite fit in your episode, expands your reach and discoverability.|
|Owner Information||Contact Information for Podcast Owner. Note that the email is public, so choose carefully.|
|Public Feed URL||If your podcast already exists - this would be the link people follow to subscribe to it. If you are launching a new podcast you won't have one yet.|
|Enclosure Prefix URL||
This URL prefix sits in your RSS Feed and makes sure that any downloads are trackable through your third party podcast metrics vendor of choice.
Often something like:
This will require an account with said third party metrics vendor!
|Copyright||Copyright notice for the content in the podcast|
|Language||Apple Podcasts uses this for discovery purposes. It should reflect the language predominantly used in your podcast.|