If your show is hosted on Anchor, you'll need to update your show's email address in your Anchor account before you can get the verification email from Podcorn.
Follow the instructions here to update the email address that is listed in your show's RSS feed: https://help.anchor.fm/hc/en-us/articles/360028557892-Adding-your-email-address-to-your-podcast-RSS-feed
After you've updated your RSS feed's email address, visit this help article to learn more about getting started with Podcorn if your show is hosted on Anchor.