Testing prelive RSS feed on Hubspot app


i want to build an email flow based on RSS feed of a site on wordpress. However,wp rss doesn’t give separate modules such as images, author name etcI so I found a 3rd party plugin to implement on wordpress as a parser solution. Now it’s on prelive version of the blog. As the prelive’s closed for public domain I need to open it for hubspot app. Opening it for hubspot’s public IP ( didn’t work obviously. What can you suggest. I cannot put the plugin on live site until it’s tested.