Coursework asks us to connect debian VM only to internal virtual network, but this seems to kill network connectivity

I hope this is OK, to ask here; I an see the rules say "No Homework Topics without detailed, and specific questions", so hopefully this will be specific enough.

Our assignment says...

After any software installation and configuration required, ‘Desktop’ should be configured to be connected only to an internal virtual network called internal’; it should use the IP address 192.168.64.10/24 on this network

But I seem to be missing something here, as when I connect to the internal adaptor instead of NAT, I lose connectivity, as shown in the second screencap...

https://i.imgur.com/oDDwYjb.png

https://i.imgur.com/MOcLUdX.png

So I guess Desktop's network connection must be made via the Server machine that we also set up, but I don't understand how we can configure that, especially when there is no IP address shown for the enp0s3 adapter when connecting to the internal adaptor. I'm really confused, because none of the machines we set up when we were doing the labs are connected like that. It seems they want us to do something that we weren't taught how to do, but maybe I am missing something basic.

Any help please? TIA