Hi,

2 FA is a must? Only I leave it empty. Can it cause problem?
> Not it will not cause any problem but to secure virtualizor panel you can enable 2 fa.

Now I make a clean install if I have a vm on proxmox it must show on virtualizor?
> After installing virtualizor panel you can import storage and vms on virtualizor panel using below wiki:
www.virtualizor.com/docs/admin/proxmox-import-guide/

Let us know if you need any further assistance.