The only steps to get player announcements to work is to enable announcements as you did.
Then add a player with a name and number, tap the big red play button next to the player and it should do a text-to-speech announce of the player name and number.
The red/green colors at the bottom of the player config screen are simply to distinguish between the two and allow you to overlap the sequence of the two as you like. There is no status indication intended there.
There is also no option to play/test the announcement on the player config screen. You must return to Walkout Song page and tap the Play button next to the player.