I have been retracing the guide you followed - apart from some phrasing and clarifications - the guide works as expected on a pristine Manjaro ARM system.
It is important to understand the guide to fully take advantage of it.
Doing some thinking - of course I cannot be sure - it could relate to apparmor.
Yesterday I tested on a pristine Plasma edition - but that edition is my custom ISO which do not include apparmor.
Either disable apparmor or see the AppArmor troubleshooting in the [root tip] [How To] Basic Samba Setup and Troubleshooting topic