There are certain preparatory tasks you must complete before you can continue with the Planning Work for The Podium Robbery in GTA Online's The Chop Shop DLC. The tasks include securing gas masks, rappel equipment, sabotaging the casino, and optionally acquiring masks.

You can always see your tasks laid out on the planning screen. However, you can not start your tasks from the planning screen, you must go to the task locations to begin them.

Instead, you can find these in the free roam.

The tasks are indicated by a green duffle bag on your map. You can complete these tasks in any order. When you go to the task location, you will see a green highlighted circle on the ground.

Walk up to the green marker, and you will get an option to interact with it to start the task.

For The Podium Robbery, you have three mandatory and one optional task.

Task 1: Gas Masks

In this mission, you must steal the gas masks from a fire station.

The fire station garage.

The gas mask crate can be anywhere inside the fire station, but it is always on the garage floor around the perimeter.

Gas masks.