Yes the roof can support your weight but there are some important considerations.
Wear flat, soft sole shoes and stay on the rivet lines. Never walk on, or try to access the roof from the end caps.
We don't actually get on the roof to wash it, we use a long handled mop. We do access the roof to re-seal any seams, penetrations, and visually inspect the plastic parts twice a year. I use a large step ladder and I know of others who use a straight ladder resting on pads or a board that spans the rib lines.
"You wouldn't worry so much about what others think of you if you realized how seldom they do."