I am unable to connect the vm to the internet. Raspbian’s network menu is different and I cannot find the netmask, gateway or dns textboxes.
Which VM? NetVM? Do you see any network adapters or wifi networks?
The menu is in principle self explaining. You can enter IP, DNS etc.
This is not a Qubes problem,(unless you have created a Raspbian
A search suggests that one answer would be to create a stanza in
interface eth0 static ip_address=10.137.0.X/8 static routers=10.137.0.Y static domain_name_server=10.139.1.1 10.139.1.2
eth0 and addresses to match your case.
This should work for a standalone.