ZXL screws and length

We are going to install new corrugated metal over CDX 5/8 decking with synthetic underlayment in a north GA location.

I have not done this before though we are carpenters by background.
Georgia Metals tells me the ZXL Woodbinder is a high quality screw to use.

Do I want to use 1 1/2 length or 2 inch?

Thanks for any input.

I built a home for my 130 chickens 3 years ago and used only corrugated metal and CDX decking mostly. I used the CDX 5/8 decking for the ‘shelves’ where they sleep. I used the 2-inch tek screws, and they fit perfectly. I used the corrugated metal for the roof and used the same tek screws. The best part about them is that they don’t rust. So if you are building anything that will have contact with water, I would recommend using something you are sure doesn’t rust. Otherwise, you’ll have to take everything out in a few years and build it over again. What are you planning to build, by the way? If you need any other advice, let me know.