Exporting a vApp from vCloud is simple and straightforward; just let me say a few words on the specifics.
Obviously we will need a vApp with at least one VM. You have to be an Org Admin to be able to export a VM.
In vCloud 5.1 you can only export from the library, using vCloud 5.5 you can also export a vApp from My Cloud.
Perform the following steps to export a vApp from a catalog:
Click on Catalogs.
Click on vApp Templates.
Right-click on the VM that you wish to export, and select Download... as shown in the following screenshot:
Click on Browse, and select a folder and a name to store the OVF export.
If you select the Preserve identity information checkbox, the exported VM will keep its UUID, MAC, and network settings.
Wait until the VM is exported.