[Samba] Ubuntu 18.04 classicupgrade help

[Carl Hunter]

I've currently got a Ubuntu 18.04 server running Samba 4.7.6 with an NT4 domain that I'd like to migrate to an AD.  I've found the following link but am struggling to match up the steps with the Ubuntu install.  
https://wiki.samba.org/index.php/Migrating_a_Samba_NT4_Domain_to_Samba_AD_(Classic_Upgrade)
I've also found this post that creates a Samba AD on Ubuntu 18.04 from scratch but doesn't have the upgrade steps.  
https://blog.ricosharp.com/posts/2019/Samba-4-Active-Directory-Domain-Controller-on-Ubuntu-18-04-Server
Would someone be able to help with some questions?  
In the first link, the "Server information used in this HowTo" section lists a bunch of settings.  I'm not sure how that matches up with Ubuntu.  
I'm not using ldap, my smb.conf file has "passdb backend = tdbsam:/var/lib/samba/passdb.tdb" in it if that's any help.  
Under the "Domain controller name" section it talks about a "netbois name =" line in the smb.conf file.  I don't have that in mine but I do have a "workgroup =" line.  Is this the same thing?
Does the classicupgrade just "convert" a bunch of files like the passdb.tdb and smb.conf files?  And unless you actually replace the files and start the AD service nothing actually changes?  
I think I should stop there.  
Thanks in advance and hopefully this makes some sense.  
Carl