probably you would need to ask the one who created this guide. DietPi is not creating kernels. A normal kernel update is done using apt update && apt upgrade. As well kernel 3.x seems to be extrem outdated. Depending on your base image, actual Debian kernel version is 4.19 - 5.x.
root@DietPi:~# apt update && apt upgrade
Atteint :1 https://deb.debian.org/debian buster InRelease
Atteint :2 https://deb.debian.org/debian buster-updates InRelease
Atteint :3 https://deb.debian.org/debian-security buster/updates InRelease
Atteint :4 https://deb.debian.org/debian buster-backports InRelease
Lecture des listes de paquets… Fait
Construction de l’arbre des dépendances
Lecture des informations d’état… Fait
Tous les paquets sont à jour.
Lecture des listes de paquets… Fait
Construction de l’arbre des dépendances
Lecture des informations d’état… Fait
Calcul de la mise à jour… Fait
0 mis à jour, 0 nouvellement installés, 0 à enlever et 0 non mis à jour.
root@DietPi:~# cat /etc/os-release
PRETTY_NAME=“Debian GNU/Linux 10 (buster)”
NAME=“Debian GNU/Linux”
VERSION_ID=“10”
VERSION=“10 (buster)”
VERSION_CODENAME=buster
ID=debian
HOME_URL=“https://www.debian.org/”
SUPPORT_URL=“https://www.debian.org/support”
BUG_REPORT_URL=“https://bugs.debian.org/”
root@DietPi:~#
Sparky SBC is not supported by mainline kernel and Allo’s official kernel always was and will be 3.10.38 as Allo is only doing minor patches to individual drivers (kernel modules), which we apply via dietpi-update when available.
I guess those instructions were meant for the mainline kernel that time, in which case they do not practically apply for any Linux system anymore, I’m afraid. The question is now if it works with Allo’s kernel OOTB or not. Please try to follow the userspace setup instructions, when available, which usually implies a console-to-framebuffer mapping and X.org configuration/calibration (install Xserver e.g. via dietpi-software install 6 prior to configuring it).