The Enrollment process for Aggregation Service has moved to the Privacy Sandbox Console. For more information about creating a Console account, please see this article.
Background
As part of the Attribution Reporting API and Private Aggregation API, encrypted aggregatable reports are processed by Aggregation Service running in a supported trusted execution environment to produce summary reports. To use Aggregation Service, you must complete the enrollment process described in this article. PLEASE NOTE: By enrolling, you provide permission to share your information with the party or parties acting as coordinator for Aggregation Service.