Friends list has four tabs. The first one shows your friends playing on the same platform and the other contains your friends playing on different systems. The other tabs are for recent players and notifications, including the important party invitees. You will also see invitations to clubs that now also work across platforms.
We throw a party and you are invited! The friend update will go live on February 19th. See our review of the friends list and the cross-platform parties!
More info: https://t.co/tuU7ftgEYc pic.twitter.com/Q6VfJ3Z1SQ  – Rocket League (@RocketLeague) February 12, 2019
To add a friend You need to know their RocketID, which combines their username with a four-digit number. This is assigned automatically even though you can change your RocketID username from an option at the bottom of the list (the number remains the same).
In October, Psyonix said it delayed its RocketID system until this year to ensure it was compatible with PS4. After Sony gave the thumb to platform games, the Rocket League players now only have to wait a week for them to form elite football teams with their friends on other platforms.
Meanwhile, next week's update also provides training options for extra modes (including Hoops and Rumble), competitive season 9 rewards and a way to see your number of weekly wins. However, an event scheduled this month has been canceled. Instead, Psyonix will focus on another upcoming event.