okeyyy! after 3hours i finally solved the problem. i was getting error like most of you guys.
error starting the web server
web server exception
tools (ALT +T )-> checkstatus (i was checking on settings > tools like an idiot for 3 hours)
chromecast : connected
server status : not running
But when i run musicbee, as administrator. (just right click > run as admin )
i can connect without problems.
Thanks for the plugin!