The phrase "crowded streets" means that there are a lot of people gathered or walking closely together on a street, making it busy and full of activity. Full definition
Everything looks authentic to the period, and you'll shed a tear of joy when you discover no lag, even in crowded streets while tackling a half dozen or more guards. (cheatcc.com)
You must successfully navigate through crowded streets and jump over obstacles to gain on your enemy. (playstationlifestyle.net)
Many prospective drivers attend professional truck driving schools, where they take training courses to learn how to maneuver large vehicles on highways or through crowded streets. (bls.gov)