Yes just buy a chunk of filter sponge on Amazon or LFS and cut to fit. Lots of good info on shrimp keeping but if you’re off to a good start consistency is a key principle – if you make changes do it slowly. It gets easier as the tank natures but small tanks are much more vulnerable to neglect and imbalances so keep in your toes and do your chores and establish good habits, don’t overfeed and you’ll be fine. For such a small tank I really recommend remineralizing distilled water vs using tap if you can.
shsuking 
Yes just buy a chunk of filter sponge on Amazon or LFS and cut to fit. Lots of good info on shrimp keeping but if you’re off to a good start consistency is a key principle – if you make changes do it slowly. It gets easier as the tank natures but small tanks are much more vulnerable to neglect and imbalances so keep in your toes and do your chores and establish good habits, don’t overfeed and you’ll be fine. For such a small tank I really recommend remineralizing distilled water vs using tap if you can.