This is something of a trick question. Most candidates chosen to fill a position are excited about the opportunity, honored to be chosen, and eager to prove their worth and contribute. However, the first 90 days are not the time to suggest improvements to a workplace you're not familiar with, a crew you don't know, or systems and processes you're still learning. Jumping in and trying to reinvent the wheel right off the bat will probably generate friction.
So, discuss the ways you feel you'll make an impact and address how you will ensure acceptance by your new team members. Familiarize yourself with the 30/60/90 rule. You should spend your first 30 days asking questions and onboarding. Next, you should concentrate on building work relationships and learning how they do things and why they do things the way they do. After your 90-day probationary period is an acceptable timeframe to start suggesting improvements.
Be sure to incorporate these points into your plan of action with AECOM. Think about the skills gap you could fill or an internal struggle AECOM is trying to resolve by hiring someone like you.