Atrium Drainage

We are in Southern California and trying to restore our double A frame back to its former glory. The atrium was enclosed by the previous owners, and the entire house was messed with by flippers. Needless to say we have a lot of work ahead of us.

Specific question (and forgive me if this is a dumb one): how does drainage work in the atrium? Most models in my tract have a significant space below the door and the front frosted panels, which I assume is where the majority of the water exits?…

Do the planters play a role in this? Is there a specific drain that should be in the atrium and run out to the street?

Thank you so much for all of your help in advance!!