Basic Steps followed:

NoMachine NX - Documentation

Also have TSClient installed and working.

Settings for TSClient are:

Protocol: RDPv5

After that, I'm taken to the Windows login page and prompted for username and password

Trying to mirror those settings in NXClient, I get the following error msgs:

NX> 203 NXSSH running with pid: 27104 (this changes)
NX> 285 Enabling check on switch command
NX> 285 Enabling skip of SSH config files
NX> 285 Setting the preferred NX options
NX> 200 Connected to address: on port: 3389

What am I doing wrong? What should I change? To What?

Terminal Server Client works

Trying NXClient because it allows for multiple sessions which may come in handy, unless it is unworkable for my system config.