@Alexey Thanks for the quick reply.
I now installed container station (was not in the manual) and the “command not found” message was gone, so that was the problem.
Tip for all newbies like me. If the storj app does not give any error on start (you only see 2 rows of log, so not really helpful), open container station and hit the play button if the container is not running and check the error message there. i.e. for me there seems to be an issue with identity. But Alexey just explained that so should be doable.