Subscribing to password protected podcasts with the IOS apple podcast app

You add a password-protected podcast just like any other that you add manually by URL. Assuming they use HTTP authentication, the app will prompt you for the username and password when you attempt to add the password-protected RSS feed.

I happen to be able to simulate a scenario in which an RSS feed is password protected by HTTP authentication and found that the Podcasts app on iOS 12.4.1 did in fact prompt for a username and password. But, here's a couple of things to consider.

If trying to add the URL doesn't result in an error, and you can see and listen to episodes, you don't need to do anything further.

If you try to access the RSS feed in a normal browser and you're prompted to login using an HTML form, rather than an HTTP authentication dialog, then you won't be able to add the podcast unless logging in with a normal browser results in the URL changing to contain your username and password or the URL changes to one with a unique ID that doesn't change and doesn't require re-authentication. If you get one of the types of URL described, that's likely the URL you'll need to use, assuming it is actually an RSS feed you're taken to when you login.

If the Podcasts app tells you the server or feed can't be found, make sure you're entering a URL that points to an RSS feed containing audio files. Being required to login using an HTML form would also likely cause this error.

Beyond that, I can't help you further without more information like the URL you're trying to use, the steps you take to add the podcast, and what happens when you try to add it. You might also consider contacting the RNIB to find out if and how you can add their feed to the builtin Podcasts app.

I tried that link and it worked as I expected it to. It uses HTTP authentication and the Podcasts app should be prompting you for your credentials (which might take a second or two) when you add the URL. It says something along the lines of "To continue receiving updates you need to sign in." If that isn't happening, it could be that you're using a device or iOS version that doesn't support HTTP authentication for podcasts in the Apple Podcasts app. However, since HTTP authentication is a basic piece of functionality, I highly doubt this is the case.

I would delete the podcast from your library completely, if you haven't done so already, restart your device, and try adding it again, making sure you include the URL scheme (i.e. "http://") and everything after the "?".

If it still doesn't work, your best course of action would probably be to contact Apple, or to make a Genius bar appointment if you have a near by Apple store you can get to, because it should be working exactly as I described. For reference, I'm using an iPhone running iOS 12.4.1.