virtualbox.org

I have a Desktop PC [host Win 10 Home] with a virtual box 6
I ran some Linux VMs... success

Can run the VM-From-PC-old.vmdk + vmx

came from using VMware vCenter Converter Standalone to Convert my sister Win 7 Home old PC to virtual machine...?

the result is two files VM-From-PC-old.vmdk + vmx

what to do to run this file as VM in virtual box 6 - host Win 10 Home?

Host RAM 8GB
Intel Quad Processor

Host PC is very Old and can Not run VMware Player

The vmx file is VMware's 'recipe' for the virtual machine. Virtualbox cannot use the vmx file. You may be able to open the vmx file in Wordapd and see what the guest settings were, then try to duplicate these settings in a Virtualbox guest.

You might also zip and post the vmx file here, someone may try to post what settings you might use on the Virtualbox guest.

Ypu may also 'export' the VM from VMware, then import it into Virtualbox. There may be less possibility for error this way, but you will have to go make another copy of the VM on the old PC.

When you make the Virtualbox guest, you would use the vmdk file as the guest's disk file.

Can review the vmx file, build a VM in virtual box with similar specs and then startup vm using vmdk file as guest hdd disk file?

That's the general idea, yes.