The JoplinApp Docker is unfortunately a very old version and does not seem to be updated regulartly. A folder access issue also prevents the app to run after install. I followed the procedure in one of the answer above to fix the issue and also to upgrade to latest version of Joplin. This is too bad that this application is not properly maintained. Link to answer: https://forums.unraid.net/topic/103022-support-joplinapp-corneliousjd-repo/#findComment-1291944