My guess would be the rail that the awning material slides into was not sealed behind it. It should have butyl tape under the whole length of it so it seals all of the screws that go through it. What you are thinking is water getting past the door seals is likely water leaking through the screw holes and running down the inside of the wall. It then exits the wall at the opening cut for the door.
Curious. Did you have the awning adjusted so it sloped away from the trailer? Or did you have the front front edge of it adjusted up high making the water run towards the trailer.
Another item to check is the rain gutter. It should be sealed the same as the awning rail or you will get the same effect.