ScoreCam uses streaming services which do not require any fees to watch the Live Stream (YouTube Live, Twitch, Periscope, etc.). The number of viewers that can watch the stream depends on the service but, currently, there are no limits.

As for privacy, you can make the stream Public, Private or Unlisted, depending on your streaming service. 

Here is more information for YouTube: YouTube: Change video privacy settings

Here is more information for Twitch: How to Private Stream on Twitch 

Here is more information for Periscope: A Definitive Guide for Private Broadcasting On Periscope Streaming