I put the JoplinPortable.exe on a bitlocker encrypted stick. When I doulbe click to start JoplinPortable, it opens the database of notes that the desktop-version on Win10 is using on the computer.
I hoped, JoplinPortable would create it's own new database on the stick itself and is able to sync with via WebDAV - am I wrong?
Thank you! Indeed Joplin (desktop) was active in the backround when I started JoplinPortable. Quitting the desktop-version was the key to start JoplinPortable the way expected.