Building a Content Matching System for Outreach Campaigns

Hi I want to build the following but struggeling a bit on how to do it. I have a client who has a giant content repository with a summary and three columns with key takeaways. Visitors and subscribers (and members but they are not included in this system) are able to download content. I want to create a system where I can match the downloaded content to the content repository and come up with a new content suggestion to start of a outreach campaign with. Do you guys have any suggestions on how to create such a matching. Idea's are more then welcome! Thanks a bunch.