Installed docker desktop on a fresh Kubuntu system with devilbox;
Having started the docker desktop and opened the devilbox shell (i.e. going into the container) write access to any folder under shared/httpd/ (corresponding mapped directory has been created by host-user) is being denied. NEW folders can be added directly under shared/httpd and hence under those recursively.
The corresponding folder for shared/https has changed credentials; before: hostuser and -group; now: user and group 100999.
Step 1: The problem can be resolved by adding a new group with id 100999 on the host and adding the hostuser to it.
Step 2: In order to also grant access for docker desktop to the shared host folder you will have to grant write-access to that folder and further down for the related group.
Also change the related group of that folder to the newly created group (see Step 1).