Your matchmaker decides which players to group up for a session. It grabs information from each player and then runs it through a set of rules to figure out the best possible match.
Anti-cheat software checks for wallhacks, aimbots, boosting, and even whether players are using scripts to cheat. It makes sure your game is fair, fun and safe for everybody.
Some anti-cheat technology may offer other services, such as reporting your churn and AFK rate (away from keyboard).
In most cases, you’d plug in your anti-cheat software with your matchmaker or orchestration system, which is usually tackled on the server-side. So none of your players will need to download or install anything.