No network from minimum net install

• I did a minimum net install, but my new system is not starting the network automatically -- No IP address with my eth0 device.
• I installed dhclient package myself but that doesn't help. I thought it should have been taken care of by the post-install of the dhclient package.
• Searching for the answer myself, I found this page, hinting that I have to write such systemd unit for myself.
• If so, I have to first understand what's systemd unit activate vs enable, whereas previously in init5, all I need to do is to install a service package and its post-install will take care of enabling the service itself.

All these have been way too complicated than it should, I believe. Somebody help please.

UPDATE:

OK, maybe the reason is that this is a minimum net install, and I don't have all those things required. Here is more info:

$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 00:0c:29:56:d8:4c brd ff:ff:ff:ff:ff:ff
    altname enp2s1
    altname ens33

$ ls /etc/netplan
ls: cannot access '/etc/netplan': No such file or directory

$ sudo service NetworkManager status
Unit NetworkManager.service could not be found.

$ ls /usr/lib/systemd/system/dhcpcd.service
ls: cannot access '/usr/lib/systemd/system/dhcpcd.service': No such file or directory

But still, if I run dhclient myself manually, I will get IP under such minimum install. I.e., the NetworkManager is not absolutely necessary, I hope. And I hope there is a fix for situation like this, whether using dhcpcd or dhclient.