Usually you will need to explicitly enable one or more physical adapters to be assigned to the Alta VM in your VM hypervisor software (such as VirtualBox, VSphere, etc.). Most of these systems have several options for how the network ports will behave - for example in VirtualBox, "Bridged Adapter" puts the guest VM directly on the network the host is on, while "NAT" puts the guest VM on an internal network to its host, where it will not be directly accessible from outside the host. Please consult the documentation on your hypervisor if you have questions.
All interfaces in the Alta guest VM will initially be configured for DHCP.