I see three options, take the pellets back and get the right fertilizer, get a spreader that works for your pellets, or broadcast the pellets by hand. But see if they're right handed pellets or left handed pellets.

Would you like instructions on how to do any of the options?

I use alfalfa pellets (rabbit chow size) as fertilizer, and those don't go through any spreader reliably. I scatter them by hand.