Elmedia Player running on your Mac will be listed on any iOS device connected to the same network. Anyone who sees your computer will be able to stream media to it unless you set up a password.
You can configure your AirPlay security settings in Elmedia Player Preferences.
No password is required to be set by default. To set it select Password from the drop-down menu and type in a password of your choice. This password will be asked on any device attempting to connect to Elmedia Player via AirPlay.
You can also choose the preferred behavior on connection: Elmedia Player will either connect and start playback immediately (Connect and Play), or prompt you to accept the connection first (Request access).