Tracking multiple documents across multiple websites

Is there a way to track multiple documents (PDFs, Word documents, Excel spreadsheets...) across multiple sites without having to go into each site individually?

Example: My company manages 80+ websites. Each website is owned by a separate company. All of these companies upload different file types: PDF, Word, or Excel). They share hosting, maintenance, and support.

Right now, I have to go into the back end of each individual site to see how many documents are uploaded and the type of documents uploaded. I would like to find a tool to use OR look at a report that shows me an overall view of documents across multiple websites. I use Screaming Frog to scan the site and that provides me a list of the number of documents and the document. However, that solution needs to be repeated by the number of sites I have.

Thank you,
Johann