Each Ryder Cup team has twelve players. Some earn their place automatically through a points list built up over roughly two years of tournament results, and the rest are chosen by the captain. Both sides set the exact split and the points formula fresh for every edition.
The two teams have historically run different systems, because they are picked from different tours. Europe has moved towards a single combined points list supported by captain's picks, while the United States has run its own points formula weighted heavily towards majors and the biggest events.
The balance between automatic places and picks has shifted over the years, generally in the direction of more picks. Captains argued that a points list rewards a long stretch of steady results rather than current form, and that pairing matters in a team event in a way rankings cannot capture.
Because the criteria are published fresh each cycle and often close to the qualifying period beginning, the safest thing to say about any particular edition is what has been confirmed for it rather than what applied last time. A player asking how to make the team is really asking about that cycle's published rules.