The player record explained

One page holding everything about one player, arranged so the useful thing is near the top.

Steps

Open a player from Players.
Read the top of the page: Next session with their RSVP, Latest note, and the radar with their own scores overlaid.
Use Assess player or New assessment to score them, and History and progress to see the trail.
Work down the sections: Goals, Home practice, Notes, Calendar, Tournaments, Forms and check-ins, Plans, Consents and Family and account.
Use the Plans links for Annual plan, Training plans, Physical testing and Development plan.

The adherence figure is built from attendance you have confirmed, never from RSVPs, so it means what it says.
The development tile shows the current overall, the change since the last assessment, and a sparkline.
Export data (JSON), Archive player and Delete permanently live in the More player actions menu at the top of the page.
Tournaments merge two sources: competitions you run, and events the player logged themselves.