In the Minecraft Launcher, select Java Edition & click 'Installations'.
Click on 'New Installation' & set the version to 'release 1.21.3'. Afterwards click 'Install'.
Click on 'Play' & launch the game. Once the game has launched, click on 'Multiplayer' & click 'Add Server'.
Enter the server name & address. Make sure 'Server Resource Packs' is set to 'Enabled'. Add the server & join.