Almost always these types of compatibility errors are cause by theme or other plugin conflicts with Seriously Simple Podcasting.
To start with a simple thing you can do is run a Theme Conflict Test to ensure that the theme isn’t the source of a problem with running SSP.
If you’ve already ruled out a theme conflict, you’ll need to check for plugin conflicts. First, look to see if any other plugins are creating Custom Post Types or RSS feeds. If so, disable those first, and then try to install/enable Seriously Simple Podcasting.
While a WP stock theme (like Twenty Sixteen) is still active, next deactivate all other plugins and enable Seriously Simple Podcasting.
Test your issue once again, and if it no longer exists, you have a plugin conflict. To determine which plugin is conflicting, re-activate plugins one by one while testing to see if the issue returns after each activation. When the issue returns you’ve found the conflicting plugin.