LinuxCNC Error

I have 2.9.3 with the 5.4.258 RTAI kernal and am getting an error when starting my mill program.

     insmod: ERROR: could not load module /usr/realtime-5.4.258-rtai-amd64/modules/rtai_hal.ko: no such file or directory 

After I got the error and copied that specific part the error changed it won't come back again.

How would I get an RTAI version of linuxcnc, I have been looking at the getting started and installing linuxcnc and haven't seen anything like that.

I am so confused right now because the documentation has instructions but it seems like packages are missing from the pre-made files, and the documentation that is stated does not work. Then when I go to forums I am being told that some things may be missing. I am so lost right now, I don't know what to follow and what to ignore, out of date info, what files do and don't work with each other...etc.

I never seen any documentation saying to use those commands in that way. I will try that and get back to you.

when I run "sudo apt install linuxcnc" it returns

Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Package linuxcnc is not available, but is referred to by another package.
This may mean that the package is missing, has ben obsoleted, or is
only available from another source

E: Package 'linuxcnc' has no installation candidate

 

Maybe it will work but I am going to try the file from the downloads page at the LinuxCNC Packages "LinuxCNC package for RTAI Kernal 5.4.258" the file is labeled as "linuxcnc_2.9.3_amd64.deb"

Do you know how you would install the linuxcnc package? I thought I knew, but I wasn't able to accomplish it.