I'll second usersmanual. I used the heavy duty vinyl adhesive available at Lowe's. No problems with the floor lifting after two years.
I would not recommend that you use the fancy underlayment. I thought I was doing the right thing by using the thin high zoot spongey stuff for sound and temperature insulation. I don't like the way the floor moves when I step on it. I have a flat floor slide out, and the seams move relative to each other because of the underlayment. If I were to do it over again, I would glue roofing felt to the plywood floor, and glue the vinyl planks to the roofing felt.
