When you run the converter, choose your source server. in "Destination System" the destination type would be "VMware Workstation or other VMware virtual Machine". Browse to the location of your USB Hard Drive/device. Run the conversion.
When the conversion completes, connect the hard drive to the network with vSphere and upload the server folder into your datastore via "Datastore uploader". Right-click on the .vmx file and click "Add to Inventory"
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