I just put down a floating type floor with engineered wood in my basement and I love it. You certainly do need to install the 6 mil vapor retarded (plastic sheets-don’t have to be black); this will help keep any moisture coming up from the slab to move to the sides and not get trapped beneath the floor. Make sure the edges of the vapor retarder run up and around the floor at the perimeter and that there is enough room so there is a chance for the floor to move and to allow moisture to escape. As far as the bubble underlayment, I chose to use a closed cell foam that came in a 3’ wide sheet. You do need some type of cushion beneath a floor like this, the thicker the more comfortable.