As ducklings, you will need to brood them like you would chicks (basically). So, you want a warm, safe, easy to access spot. If that is your barn then great. Keep in mind that some losses may occur, especially when you are new to ducks. Shipping can be hard on little ones.
I would try to...
Read this https://www.backyardchickens.com/t/750869/raising-and-caring-for-ducklings#post_10611711
And have a plan for what may happen if you get more than 2 males in the bunch. You are likely to get mostly males with straight run and too many males will overbreed females and can kill them...