I'm really bad at this one! (Like a lot of games in this jam, I'm finding...)
I didn't notice the instructions on the side immediately, and I think I actually did better when I wasn't actively using space.
One thing to note, the player also loses points/bounces/attempts when the ball hits the sides of the catcher. This may be by design, but given it can knock into both sides before being collected it feels a little bit like being punished for succeeding.