Your subdomain is the required information (see the following screenshot) when you register your account, it is: and this is also the URL of your Podbean site. All your posts will show on this site.You can change your subdomain later, but it will change your podcast url which can have some negative effects, so consider setting up a subdomain that you will likely want to keep. 

The subdomain is always needed when you encounter an issue and contact Podbean support so that we can figure out the issue quickly for you.