I'm having a similar issue. This is the first time I've installed this container and get the same message when I try to open the web GUI. I tried deleting "perms.txt" but that seems to have no effect. The minecraft folder appears to be fully fleshed out and I'm not seeing a \security folder. I am able to connect to the server with the Win10 client.
I've tried looking through the documentation I can find, but I'm not coming up with much. Any help would be appreciated, even if it's just pointing me at the thing I need to read. Thanks!
