The Wizard King summons Asta after his work dealing with the Eye of the Midnight Sun. Yami tells Asta he can come with him to the royal capital, since he has to go to a conference of all the Magic Knights Captains.
That would've been impossible unless 
they had help from the inside.
.وذلك مستحيل إلّا إذا حصلوا على مساعدة من الدّاخل
So etwas wäre nicht möglich
ohne einen Helfer in der Hauptstadt.
E questo non sarebbe stato possibile,
senza un aiuto dall'interno.
Teria sido impossível sem ajuda de dentro.