One of the required fields of a feed is the Website field. When creating a new feed, you'll need to provide a link of your choice.This can point wherever you'd like.
Be sure to include "https://" at the start of the URL. Some apps won't link correctly if that's missing.
A few options:
Your business website
The login page for your product/course
Your Facebook page
Your Instagram page
Google.com (it really doesn't matter what's in this field, as long as it's a link)
It appears in a few apps in different ways. Some examples:
Apple Podcasts
Scroll to the very bottom of the episode list and you'll see "Information". The "Show Website" will have the feed title clickable with your link.
Google Podcasts
At the top of episodes is a globe icon that links to your link.
Overcast
At the top of the episodes, your link is shown under the hosts' names.
