New roof with Romano Pans and Mission tiles glued and not fastened with copper?

Hello, I am installing new Romano Pans with Mission tiles – El Camino Blend on my roof. I had discussed with my contractor copper fasteners, but now he says they a glued down and don\\’t need copper fasteners? Is that correct? I live by the ocean in Hawaii and we have hurricane winds sometimes. Will glue onto of the Boral ice and water shield be enough? Thanks