So a parking violation is your proof that the car was a getaway car.
I feel silly even asking you this but were is your proof there was a shooting team inside the TSBD.
The "NO PARKING...." zone was close to the corner. No vehicle could have gotten in front of this car without hanging out onto Elm St. This ensured the "getaway" car could immediately turning onto Elm St when traffic was flowing again. They knew nobody would take this "NO PARKING...." spot, and they could pull into it at the very last moment. This spot alongside the Island was close to the corner, and close to the "wide open" Huge Gates. The Huge Gates provided clandestine entrance and exit to the TSBD.
The "getaway" car was picking up a shooting team. Shooter + Spotter. Shooter + Spotter exited the TSBD via the Huge Gates, and then intended to get into the "getaway" car that was mere feet outside the Huge Gates.