Peer-to-peer with rollback netcode. One of you hosts, the other joins with the code.
Accounts aren't available in this copy of the game.
You don't need an account to play. Signing in shows your name online, saves your settings and trial progress, and tracks your online matches.
This is the name opponents see online.
Type their display name. Once they add you back, you're friends: you'll see when they're online and can invite each other to rooms.