Episodes 1-4 are freely available on Youtube (https://www.youtube.com/@hardcoregameofthrones1070/featured), and it seems that episodes 5-8 used to be behind a paywall at howl.fm (shut down) and then apparently stitcher premium (also shut down).
As a fan of both the Hardcore History podcast (which this parodies very well) and also Game of Thrones, I really enjoyed the first four episodes, but it does not appear that I can download or purchase these lost episodes anywhere at the moment.

It looks like episodes 1-3 are on some earwolf thing on iTunes, and I expect they are probably available on other podcast apps as well. It's episode 5-8 that I can't find.

The podcast comes with a disclaimer: This work is a parody of Dan Carlin’s Hardcore History Podcasts. Mr. Carlin is not associated with this production and any views or opinions presented in this podcast are solely those of Alex Berg and Jason Greene. It's possible that they might have copies, but I don't know who they are or how to get in touch with them.