OVA
Important OVA Info
Use OVA Format Version 2.0 SHA256 digests for vmdk and ovf file in the .mf file Right now, at least on VM Workstation Pro 15 using ubuntu cloud image https://cloud-images.ubuntu.com/releases/bionic/release/ubuntu-18.04-server-cloudimg-amd64.ova you need the ova filename to be the same as ovf, vmdk, mf.
tar cf myname.ova myname.ovf myname.vmdk myname.mf
VMWare Pro had strange issues importing into tar OVA even using myname-disk001.vmdk - Who knows as to the reason. Platforms suck.
More Info
https://www.vmware.com/support/developer/ovf/
tar cf demo.ova demo.ovf demo.mf demo.vmdk demo.iso
ovftool --schemaValidate Output/demo.ova
http://www.doublecloud.org/2015/10/vmware-ovftool-as-development-tool-good-and-bad-parts/
Using virtualbox
Create vm
Export to ova format like above
vboxmanage export bionic --output bionic.ova