API for my inventory management platform

First time poster, I apologize in advance if my question isn’t clear enough. I’m working on launching an automotive internal inventory platform for the sales teams. My question is, if Reynolds and Reynolds holds the API, do I need permission from the dealership or just pay Reynolds directly?

During market testing, I was showing dealers how I was using the dashboard I created for my store and how I updated it manually. Several agreed to give me the access I would need to see their inventory. I’m a little confused on what next best steps would be.