A company runs business applications on AWS. The company uses 50 AWS accounts, thousands of VPCs, and three AWS Regions across the United States and Europe. The company has an existing AWS Direct Connect connection that connects an on-premises data center to a single Region. A solutions architect needs to establish network connectivity between the on-premises data center and the remaining two Regions. The solutions architect must also establish connectivity between the VPCs. On- premises users and applications must be able to connect to applications that run in the VPCs. The solutions architect creates a transit gateway in each Region and configures the transit gateways as inter-Region peers. What should the solutions architect do next to meet these requirements?