LOL, you obviously don't understand how intellectual property works. UAE reimplements everything from scratch therefore they don't need anyone's permission. They don't need permission for anything except perhaps to use the name 'Amiga' which they don't. Neither does AROS. Oracle spent millions trying to sue Google for reimplementing Java from scratch in Dalvik/Android, and they lost.
It's not a port, Ratalaika and Factor 5 say it's running under emulation in the many interviews they've done. So either they've written their own amiga emulator from scratch in less than 2 years for one game only, or they're using UAE.
UAE runs on ARM processors. Jesus christ, please don't comment if you're just going to make a fool of yourself.