FIFA 21 Companion is the official companion app for FIFA 19, which you can use to manage your FUT team and much more. Obviously you'll need an EA account and the FIFA 21 game for PC, Xbox One, Xbox 360, PlayStation 3, or PlayStation 4.
From the app interface you can put together your team's lineup, participate in the transfer market, or go into the online store to buy FIFA points. In other words, you can set up your next game so that as soon as you get home you can start playing without having to do any management on your PC or console.
FIFA 21 Companion is a practically indispensable app for any hardcore gamers of FIFA 21 in FUT mode. The app interface is also quite nice-looking – some might even say elegant.