Start retroarch > press load core > choose download core and download desired core(they’re organized alphabetically so scroll down for nintendo, sony consoles etc.) > press load content to browse your phone memory for the game you wanted to play.
^Above steps are only needed the first time.
*If you’re confused about which core to choose you may find this handy in helping you choose the best option(or learn anything about emulators really).
Go to the online updater, hit the “Update Core Info Files”, let it finish and try again.
It’s worth noting that the Play Store version of RetroArch is a bit kneecapped by some Google restrictions, I don’t know if that’s the root of your issue but can try grabbing the apk from their website or from F-Droid.
If that doesn’t work, try Lemuroid. It’s an easier to use interface on top of a couple RetroArch cores
The playstore version got screwed by google. Try the one on their website it works fine for me.
