Ask HN: How legal is this?

I'm developing a web site and mobile app for road travelling and I wanted to include service areas, which, not being the focus of my project, represent very useful auxiliar information.

It just so happens that I found a website that has these service areas and then has free-to-download files for tomtom and garmin. These files don't contain all the info the website does though. So, I took these files and I wrote a crawler that goes to the website and gets the rest of the information for each entry. So now I have all this information to include in my product.

Now, I've noticed that despite the website being free, they do have a paid mobile app with this data. So... I'm not sure they will be very happy that I include it somewhere else, but is it actually illegal? The files are free to download and the website free to access (without any need for registering).

I haven't made my mind on whether or not my project is going to be just for me or if I will have greater ambitions for it, but I'd like to be prepared just in case.