You'll need to answer questions flexibly in the interview, I'd say.
Literal
Interview [at-では] you [topic-は] flexibly must-answer [probably-でしょう].
臨機応変 ('adapting to circumstances, flexibly') is a four-character compound (四字熟語) built from 臨 ('face') + 機 ('opportunity/moment') + 応 ('respond') + 変 ('change') — 'facing the moment, responding to change.' Used as an adverbial with に. ~なくてはならない is another obligation form, slightly more deliberate than ~なければならない.