Use the A and D key to move the red paddle. Use the arrow keys to move the blue paddle. Player 1 is the blue paddle. Player 2 is the red paddle. Sorry I got them mixed up when positioning them.
Credits: 1. Scratch 2. @hoshe6 for asking for a 2 player version of the first one I made which you can play at: https://scratch.mit.edu/projects/406152703/