A large company operates workloads across hundreds of AWS accounts, with each account containing VPCs that include both public and private subnets spanning multiple Availability Zones. NAT gateways are established in the public subnets to facilitate internet access from the private subnets. A solutions architect is tasked with implementing a hub-and-spoke network architecture where all private subnets in the spoke VPCs must route internet-bound traffic through an egress VPC. The architect has already set up a NAT gateway in the egress VPC within a central AWS account. What additional steps should the solutions architect implement to fulfill these connectivity requirements?