>Nun hätten die Behörden enorme Schwierigkeiten, die Krise zu meistern, sagte Innenminister Bam Dev Gautam im staatlichen Fernsehen
I would translate that into:
"Now, the government had big difficulties to master the crisis, as the Home Secretary Bam Dev Guatam stated in public television".
Usually, "nun" can be a kind-of-synonym with "jetzt" (now), but this is not always the case. Sometimes it can be used as a filler word (a little like "well" in English). I think that these are the most common ways to interpret "nun".
Maybe it can help to try replacing it with "jetzt" and see if the sentence still makes sense, or to think about whether the sentence makes sense without "nun" (e.g. "Nun muss ich nach Hause gehen" actually kind of becomes a question when you remove the "nun")