The prerequisite step to adding additional users to a Google Cloud VMware Engine's vCenter (GCVE) is to add a user in Google Cloud Platform Identity and Access Management. This will allow for the user to be added to the vCenter and properly authenticated. To add additional users to a GCVE vCenter, a prerequisite step is to add a user in Google Cloud Platform Identity and Access Management (IAM)1.This is because GCVE uses Google Cloud IAM to manage access to the private cloud2.The user must have the appropriate IAM role, such as VMware Engine Admin or VMware Engine Viewer, to access the GCVE portal and vCenter2.The user must also have a Google account or a Cloud Identity account2.After adding a user in Google Cloud IAM, the user can sign in to the GCVE portal and launch the vCenter web console2.The user can then perform operations based on the assigned vCenter role and group3.Reference:1: Adding users to Google Cloud VMware Engine,2: Managing access to Google Cloud VMware Engine,3: Private cloud vSphere permission model