It can be problematic finding a url for an internet radio station that works with Roon. Many stations have urls tied to a pop up streaming device , and those won’t work with Roon. Sometimes it can be difficult to find any “normal” url at all for a stream.
I suggest Roon add a pre setup index of Internet radio stations and their urls - much like what exists already in Logitech Media Server in it’s internet radio function. Then you can just click on an existing url from the list in order to listen or to add it to your library.