Your public station page or embed widget → that is the listener link.
If the public widget still asks for a username/password, it is likely the old player bug or a cached/wrong URL. Try another browser, or contact Caster.fm support with the exact public player URL.
The Windows app you used to start streaming is the broadcaster. Listeners should use your public web player or widget, not that app and not the token-protected stream link from the dashboard.