First of all, make sure your Animal Crossing game has actually been updated to the latest version. You can do this by looking in the top right corner of your screen from the main menu, which should say ‘3.0.0’.

If you have opened up your Animal Crossing: New Horizons game in a fit of excitement only to find that you don't yet have access to the latest ACNH update, don't fret. You can update your game manually to trigger the 3.0 update and start playing.