Need help to set up public library on kobo

I have a Kobo Mini and I never tried to set up my public library (as I had a dedicated button on my Sony ereader) so I downloaded Adobe Digital Editions 4.0.
It does not open in Adobe Digital Editions as I followed instructions how to set it up.

I think the problem is here; Because I have Reader (app on Mac for Sony reader) it goes to this library. Do I uninstall Reader, or what do Sony readers do?