How best to care for a mother robin, or should I just let it be?

I have a mother robin who has built a nest on top of my utility door (on my balcony), in the angle between the door and the wall. I have secured the door so it will not swing in either direction and cause the nest to fall. Is there anything else I can do? Should I put a shallow basin of water out on the table for her (I don’t want to attract mosquitos)?

Also, she leaves the nest to go get food (I’m guessing)...Is this normal? I thought birds had to sit on their eggs the whole time so they stayed warm, but maybe the father got killed? Maybe they can leave them briefly when it’s warm during the day? (Sorry, that’s a lot of questions all rolled into one…)