We can visit the site www.rataalada.com from The Batman post credit scene and it has some message from Riddler I believe. I was able to download a ZIP file from
hostiles
barry-lyndon
the-district
straight-outta-compton
a-dogs-purpose
inception
adventures-of-zatoichi
screenplay
action
collateral
the-alienist
scream
coma
step-up
birds-of-america
the-last-boy-scout
countdown
the-dark-valley
alita-battle-angel
pk
interview-with-the-vampire
full-house
zero-dark-thirty
travelers
the-insider
elysium
ww2-in-hd-colour
sully
clear-and-present-danger
spider-man-far-from-home