I hesitated to report the adhesive I used on the aluminum side skin until I was sure it had the properties I thought were needed.

I'm delighted to report that Henry 663 Brand outdoor carpet adhesive has what it takes. It goes on easily with a trowel. It dries slowly allowing time to position the aluminum. It keeps a very tacky consistency which allows the aluminum to expand without ripping your plywood wall underneath. It is waterproof & effectively acts as a water barrier. It is available at Home Depot for $13 a gallon.
Side Aluminum Skin Adhesive