How to Converge an existing VMware vSphere environment to VCF 9.0 step-by-step.

We will see below (step-by-step), how to Converge a vCenter Instance and ESX Hosts to vSphere Foundation Platform.
In our case the target VMware Cloud Foundation we converge on is 9.0.2 version.

To successfully converge your existing vCenter instance and ESX hosts, you must ensure that you comply with the prerequisites, follow the procedure, and perform the next steps.
Verify that your existing configuration is supported and you satisfy the minimum component versions. See Supported Configurations in Converging Existing Virtual Infrastructure to a VCF or a vSphere Foundation Platform.

Last but not least, check Supported Scenarios to Converge to VCF.

Before to begin, a quick tip to keep in mind:
The first step to implement VCF 9 is to deploy the 'VCF-SDDC-Manager-Appliance-9.0.2.0.25151285.ova' file, which serves as the installer, as shown here.
If the VMware Cloud Foundation installer appliance is deployed on one of the hosts in the management domain. During the deployment process, the installer appliance will be converted into the SDD Manager appliance; otherwise a new SDDC Manager appliance will be deployed within the vCenter being converged.
In the case illustrated below we deployed the VCF installer outside the vCenter to be converged.

Let's start:
Access the "VCF Installer" (how to download, deploy and configure VCF Installer available here) UI via browser (https://<appliance-ip>), and log in.

Check that the depot (in our case the online depot) is correctly configured, and binaries are successfully downloaded.

Expand "DEPLOYMENT WIZARD" and select "VMware Cloud Foundation" (1).

Select "Deploy a new VCF fleet" (2) > CONTINUE (3)
In our case, the vCenter that will be converged will also be the Management Domain's vCenter.

Select the existing components (in our case only vCenter)(4) and click "NEXT" (5).

Fill in the "General Information" (6), selecting the version, entering the new name of the VCF instance, the management domain, etc.
Select the "Deployment model" (in our case, since it's a LAB, I selected Standard (Single-node)). Then proceed by clicking "NEXT" (7).

Select the correct size of the "Operations Appliance", fill in the FQDN (8), passwords and enter the FQDNs for the "Fleet Management Appliance" (9) and for the "Operations Collector" (10) Appliance. Press NEXT (11).

In this case, since it is a LAB, I skip the installation of "Automation"(12) appliance and continue by pressing NEXT (13).

Indicate and enter the credentials of the existing vCenter that you want to convert (14).

Accept the certificates (16) and confirm (17).

Enter the required information to deploy the NSX appliance (18) (19) to the management domain and continue by pressing NEXT (20).

The VMware Cloud Foundation installation appliance is not deployed on one of the hosts in the management domain. A new SDDC Manager appliance will be deployed. Enter the required information (21).