At the main menu click Freeplay and then do Mira HQ.
As soon as the game loads go to the Laptop, open the Laptop, click on Cafeteria, add the Empty Garbage task, back out of the menu, and walk North about 4 steps for the task.
It is the fastest task that you can complete and you will not spend any extra time trying to complete or get to.
You can either stick with default Crewmate or use guardian angel, engineer, or scientist. It does not matter.
You do need to load into an online game once and then back out before going to Freeplay.
You can also change between Imposter and Crewmate freely if you decide that doing tasks becomes to boring.
You can also back out or quit at any time without worry either.