I try to download them from browser, no luck, the app? no luck either.

SunstrikeHybrid, probably because "flash" being removed at the last day of december 2020? I was deinstalling its components a while ago, while other webpages even still refer to info like "just download flash to view file xy". Being excited what happens to flash-referred games on itch-platform in that case?

So far I've also just tested and played browsergames here so far. Maybe it depends on free space or RAM of your device?