Maritime plaza used to have a shuttle that picked up in front of the Navy Yard metro, I think it still does, whoever you are visiting should have a sheet that says when/where pickup times are.

I work there and usually just walk up M street from Navy Yard when I need to go into the office, it’s a straight shot up M street. If you have any Flex Time coming or going the trail behind the navy yard that leads to maritime plaza is a pleasant walk