Do I need to use the zero upgrade wizard do it? In the past for an upgrade I would simply replace the following folders after making updates to various "INI" files and then load the DB. Is this still correct?
Yes exactly the zero down time upgrade is there for production to avoid any downtime.
If this is for UAT you can still upgrade manually with replacing the file, adapt the INI files and load the DB.
This still remains a simple way to do the migration.
But more time you will take to do it more you will have some downtime.