Remember, "Éxito" is a term often applied to music "hits" but whose principal meaning is "success".
In the case of the NY radio station, "Exitosa" is a play on that music term but really only means "Successful". A woman who has a great career or does something outstanding is "exitosa". (Remembering that Spanish is a gender specific language and a successful man would be "exitoso".) A radio station ("emisora" or "estación de radio") is feminine.
"Exitosa" has no prior meaning in the area of music, in fact. I know of only two radio operations before with that name. The name has been used in (and has been for 40 years or more) in Panamá.
La Exitosa Panama | Panama City. That is a mostly reggaetón/pop station. In Peru, the "Exitosa" name has been used a bit over 10 years by an FM operation that features news, sports and commentary.
Exitosa Noticias - Noticias del Perú y el Mundo | Radio | Tv en vivo | Podcast