Just trying to get some suggestions on whether I should float or staple this product. In the installation instructions it says to lay 6m poly underneath for the staple install, but wouldn't stapling kind of defeat the purpose of the moisture barrier as it would put holes in the poly? As for the floating install, I am just concerned about the mess with the glue and also maybe the hollow sound? Suggestions/recommendations please.

Use a product called V-LOK. The heat of the staple passing through this underlay causes it to seal around the staple (in theory at least). Seems to work cause we have never had any trouble related to this product.
Should be available where you bought the flooring.