Yes, MANDATORIES is a Scrabble word!

Letter values in Scrabble US: M 3, A 1, N 1, D 2, A 1, T 1, O 1, R 1, I 1, E 1, S 1.

Is it a valid word?

MANDATORIES is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

the recipient of a mandate
a territory surrendered by Turkey or Germany after World War I and put under the tutelage of some other European power until they are able to stand by themselves