You cannot get the shoes upgrade until you repair Freddy in Parts & Service and get the Party Pass. Once you get the Party Pass, Vanny will remove the barriers from the Atrium. From the Atrium you will want to go to the door that leads to Roxy Raceway. This is the large red door on the second floor right next to Fazer Blast. When you enter the door go straight down but do not go through the next door. Instead turn right and go straight down and you will come to another door. 

Enter this door and you will find the Glamrock Beauty Salon, as well as a ton of security bots patrolling around. Call Freddy, and hop in so you don’t have to worry about getting caught. Then enter the salon and go to the door under the “Hair & Makeup” sign. Exit Freddy and enter the door on the right next to the lockers. Inside this bathroom you will find a present with the shoes upgrade inside. With that collected you have now unlocked true speed!