Is is prempt or preempt ??

Hi,
My first post here...
I have Mint 19.3 running in a VM VirtualBox on Windows 10 Pro. I am following instructions to get stretch 2.7 preempt as detailed on buildbot.linuxcnc.org/

The Buildbot Packages List chart near the bottom shows to use this for my situation:

2.7 branch (stable)

Stretch (arch: amd64, i386)
uspace: realtime with RT-Preempt, and simulation

deb buildbot.linuxcnc.org/ stretch 2.7-rtpreempt
deb-src buildbot.linuxcnc.org/ stretch 2.7-rtpreempt

Note the (I believe) correct spelling of rtprEEmpt, not rtprEmpt. However,
when I set the needed repositories,

and did sudo apt update, I got these two error? / warning messages:
W: Skipping acquire of configured file '2.7-rtprempt/binary-i386/Packages' as repository 'buildbot.linuxcnc.org stretch InRelease' does not seem to provide it (sources.list entry misspelt?)
W: Skipping acquire of configured file '2.7-rtprempt/binary-amd64/Packages' as repository 'buildbot.linuxcnc.org stretch InRelease' does not seem to provide it (sources.list entry misspelt?)

Note the misspelling of rtprempt, (and ironically, misspelt is also misspelled. )

When I searched the forum for prempt and preempt, I found it most-often "misspelt" as prempt,

Which is it, and what can I do, if anything, to correct the failure to acquire the amd64 package? (Or does it even exist at all, regardless of how it's spelled?)

I'm a bit of a NOOB, but I was able to install the 2.7 stretch 64 bit on Ubuntu 20.04.1 in a VM after much folderal, mostly because of missing dependencies (Python 2.? in particular, (which I found a repository for on the net and added that. So I don't think I really need to worry about this warning anyway, but thought I'd ask re the spelling error. I imagine I'm not the first to run into this.
TIA for any help.

Thanks tommylight,
I actually used your excellent instructions in that post to get a successful install of linuxcnc on Ubuntu20.04.1 in a VM on my windows 10 OS. I'm so appreciative for all the work you did to help us all. I had to add a repository to get some of the python stuff (python-gst-1.0) I found this web page that helped with that: packages.ubuntu.com/bionic-updates/amd64...hon-gst-1.0/download
In Synaptic / Add Repositories, I added:
URL: mirrors.kernel.org/ubuntu
Dist: bionic-updates
Components: bionic-updates main universe
And... Bob's your Uncle!
Thanks again - Without your post I would have given up after days of trying to wrap my head around this stuff.

Tommylight, To answer your question, "Why 2.7?" - The buildbot page says 2.7 is the stable release, and 2.8 is listed as (next release, being stabilized). So that's why I was going for that one. But I will do as you suggest, and use the 2.8 link in your post. Thanks.

Checking the linuxcnc.org page

www.linuxcnc.org/2020/12/02/LinuxCNC-2.8.1/

Unfortunately the Buildbot page is a version behind. I did post an update after 2.8 was released but it didn't get incorporated...

Tommylight,
I think maybe both of these pages need to be updated.
buildbot.linuxcnc.org/
www.linuxcnc.org/downloads/