simply did not connect. I tried first to connect it as master source leaving the master username field empty in Airtime and setting the ip, port (8010) and password, mount point.
then I tried as show source in the same way on port 8020 but no way
You cannot leave master username field empty in Airtime. If your client doesn't have username field, then fill username field with "source". Most client's that doesn't have username field sends "source" as username.