Support for ublock is only available on Android's Firefox

Not just on Android, I'm using it with uBlock Origin on a GNU/Linux phone as well. Only iOS is an exception.

i'm using ublock origin in chromium for desktop linux and firefox for desktop linux

They're talking about mobile. Since Apple doesn't let browsers use their own engine, uBlock Origin doesn't work on Firefox for iOS, only on Firefox for Android. On the desktop, it works everywhere.