Apologies. It's easy to miss the title when reviewing posts here.
From what I know, older versions of iTunes prior to 12.7.2.58 are no longer able to access the store due to security concerns. This supports my theory that it may be why you cannot access new podcasts.
You are using a very old version of iTunes. Even if you're still using Windows 7 (or 8), there is a later version of iTunes that you could use. iTunes 12.10.11.2, which you should be able to download from here.
If you are using Windows 10, then I recommend that that you use the latest version, which (on the day of writing) is 12.12.9.4 which you will find here.
They are both Apple links.