Yes, UNAU is a Scrabble word!

Letter values in Scrabble US: U 1, N 1, A 1, U 1.

Is it a valid word?

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

a sloth of Central America that has two long claws on each forefoot and three long claws on each hindfoot
relatively small fast-moving sloth with two long claws on each front foot

Also: two-toed sloth, choloepus hoffmanni, choloepus didactylus.