Translation:The famous singer arrives in the building.
"Arrive in" is correct English, and "arrive into" is not (quite). Since this is a Hungarian course, and not an English course, however, I think Duolingo should be a little flexible as far as allowing direct translations, so long as they are understandable.
I certainly agree that it should at least accept the correct "arrive at" or "arrive in", which it does not consistently so do right now.
"into" should be accepted, as the direct translation of the Hungarian (and completely understandable). "At" should also be accepted, since it is the correct preposition to use in English (and "to" or "into" are not technically correct).
I'm a bit annoyed at the "arrive" thing. Duolingo sometimes only accepts "at", and sometimes only accepts "into" or "to". It's only a guess as to which to write.
What we're trying to do is understand how a thought in English, like "arrived at the building," translates into Hungarian. As such, Duolingo needs to teach us that an affix like -ba/be is sometimes used where we would use "at", even though it's more generally thought of as "to" or "into".