The following procedure will guide you through the steps that are required to configure vCenters in a Linked Mode configuration:

1. Go through with Stage 1 of the installation by deploying a new VCSA.
2. On the Install - Stage 2: Set up vCenter Server Appliance with an Embedded PSC screen, click Next.
3. On the Appliance Configuration screen, specify a Time synchronization mode and enable SSH access (disabled by default).
4. On the SSO configuration screen, choose to Join an existing SSO domain. Specify the FQDN/IP of the peer PSC, its SSO domain, and the administrator credentials:

5. On the Configure CEIP screen, choose to uncheck the Join VMware Customer Experience Improvement Program (CIEP).
6. On the Ready to complete screen, review the settings and click FINISH to initiate the configuration:

7. Once the setup/configuration is complete, you will be presented with a confirmation screen, as well as the URL (https://FQDN of VCSA:443) to vCenter's Getting Started page. Click Close to exit the installer.

This finishes the Linked Mode configuration:

Now, when you log in to the web client, it should list all the vCenter servers in the same PSC domain.