Help me install on Raspbian 10 - via Rasberry Pi 3B

I'm following the instructions here which I think are out of date:
linuxcnc.org/docs/html/getting-started/g...lling_on_raspbian_10

After adding the key, then the repo and doing an apt-get update, this happens:

root@raspberrypi:/home/pi# sudo apt-key adv --keyserver hkp://keys.openpgp.org --recv-key 3cb9fd148f374fef

Executing: /tmp/apt-key-gpghome.HaA1MP2Wl8/gpg.1.sh --keyserver hkp://keys.openpgp.org --recv-key 3cb9fd148f374fef
gpg: key 3CB9FD148F374FEF: new key but contains no user ID - skipped
gpg: Total number processed: 1
gpg:           w/o user IDs: 1
root@raspberrypi:/home/pi#
root@raspberrypi:/home/pi# sudo apt-get update
Get:1 linuxcnc.org buster InRelease [28.5 kB]
Hit:2 archive.raspberrypi.org/debian buster InRelease
Hit:3 raspbian.raspberrypi.org/raspbian buster InRelease
Err:1 linuxcnc.org buster InRelease
  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3CB9FD148F374FEF
Reading package lists... Done
W: GPG error: linuxcnc.org buster InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3CB9FD148F374FEF
E: The repository ' linuxcnc.org buster InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure( manpage for repository creation and user configuration details.
root@raspberrypi:/home/pi#


Help please!

That seems to be the wrong key, where did you get that from so we can remove it?
Try these
forum.linuxcnc.org/38-general-linuxcnc-q...-05?start=280#212635

linuxcnc.org/docs/html/getting-started/g...lling_on_raspbian_10

Within this URL.

I'm still not sure what to do. Are these URLs correct in that same link?

Is it even possible to install Linux CnC on Raspbian?

Thank you, info seems to be recent so i am not sure exactly what is correct, maybe someone else can shed more light on this?
There should be some ready made images for RPI4 (some mention RPI3 also), but since i never used them i will refrain from "helping".
Sorry.

No problem, amgio. Thank for the info.

I suck at linux and this is linux basics stuff so some linux geek might have pity on me and give me a hand.

dudesquat wrote:

No problem, amgio. Thank for the info.

I suck at linux and this is linux basics stuff so some linux geek might have pity on me and give me a hand.

Sorry, I dont have any pity, but I do have empathy because linux is hard.
linuxcnc.org/docs/html/getting-started/g...tml#_normal_download
I will suggest downloading the pre-made image for rpi. Keyserver, I dont know what it is exactly, but i can assume it has to do with apt-get update.