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
batman-v-superman-dawn-of-justice
army-of-the-dead
the-great-dictator
colossal
izombie
spanglish
stree
flash-of-genius
antz
the-phantom-menace
heavyweights
alvin-and-the-chipmunks
blood-diamond
killing-them-softly
masters-of-sex
easy-rider
notes-on-a-scandal
this-is-england
the-expanse
zombieland
cupcake-wars
mrs-doubtfire
lucifer
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limelight
the-cat-in-the-hat
stargate-1994
pan
poltergeist-2015
silent-movie