ls: cannot access ‘/home/james/Downloads/nomachine_8.16.1_1_amd64.deb’: No such file or directory
Means the file is not in that directory.
you could try ls /home/james/Downloads/nomachine*
If you get the same response the file is somewhere else.
What you will need to do is work out where you saved the file to.
In firefox click on your downloads, click show file in folder, make a note of the folder that the file was actually downloaded to.
Just for reference, the Linuxcnc install is plain old Debian 12, the only difference being that it has Linuxcnc pre installed and somethings like libre office are not installed and a few things you wont even notice. I made the current RPi images for Linuxcnc.
Now……..I would wonder why you would want to run another “server” on a machine running a time critical application such as Linuxcnc. I would be more inclined to install Putty on the windows machine and log in via ssh. Midnight commander can be used to browse the file system and edit files, ssh is enabled by default on a Linuxcnc install.
I would advise against running a job on a cnc machine remotely, mainl being possible damage to your cnc machine if things go pear shaped.