Vented Faucet for Hedpack by Midwest Brewing and Winemaking Supplies

What is the outer diameter of the spigot opening?

How do you install this on an hd5 5 gallon water jug? the lid has a hole about the right size, but there are no threads, it won't hold.

How does the venting work? Does the tube somehow allow air to flow into the bottle when the spigot is opened as liquid comes out?

I bought this to go with my 5 gallon Hedpack water jug, was this a waste of my money or did i get the wrong part?