I believe the data is considered public domain. Supercharge.info just collects it from various sources so that people can find all supercharger information easily. So there’s nothing wrong with relying on Supercharge.info as a data source, and there are no strings attached. There are even multiple other apps that already use Supercharge.info data, including on the Apple app store and on the web.
I would recommend letting people know the data comes from supercharge.info so they can use it on other devices (for example I use an app instead of this website when on my phone), but that is optional. And donations are completely optional too; most if not all funding is put towards expenses as far as I know.