We have found out that Overcast uses a very odd way of validating password protected RSS feeds. You have to modify the Feed’s URL before submitting it to their system.
If you are on an iOS device the official Podcast app really does it very well but if you have to use Overcast then you need to amend the Feed’s URL to include your username and password before you submit it.
The format is
https://username:password@[restof feed link].
For example, if you wanted to add D&D is for Nerds Vol 4 Burried Beneath would be:
Note: As your username is your email it already has an ‘@’ in it. Your formatting will be slightly different as you need to replace the @ in your username with %40 This means it would look like the below: