By default only course authors may create episodes. Course participants can download them, comment on and assess them. If you want your course participants to create episodes as well just deactivate the check box "Locked for learners" in the section "Read and write." Course participants will not be able to edit episodes created by themselves. Only course authors or moderators are allowed to make modifications. In the section "Moderate" you determine who will have the right to moderate a podcast. This means that a course participant will then be able to edit that podcast as well as delete all episodes and comments.
These settings are only relevant if episodes are created within OpenOLAT. When embedding an external podcast it will not be possible in OpenOLAT to determine who will be allowed to create episodes or not.
Course participants can periodically check via the podcast's Newsfeed if there are new episodes before downloading them. On the homepage of your podcast you will find various possibilities to subscribe to a podcast via the feed URL of an online service such as iTunes.
You can also use this podcast course element to include an external podcast. Just select "Include an external podcast already existing" when editing that podcast for the first time. In the field "URL" you have to indicate the feed link of your external podcast. Usually this is a URL with an .xml add-on. Episodes will then be displayed within your course element.
Once you have decided on what kind of podcast you plan to embed (create episodes yourself or embed external podcast) you will not be able to modify your choice later on.