HTTPS with draw.io

Hi everyone,
I’m trying to run the drawio app with HTTPS enabled. It seams like this should be working because the container opens to ports: 30090 for http and 30091 for https. But on port 30091 I get just the message, that no server is responding.
I also tested the same docker container on a Debian machine and https is working there (so this doesn’t seam to be a general problem of the container).
When looking into the container logs, I’m getting a lot of “permission denied” errors like these:

/docker-entrypoint.sh: line 16: /usr/local/tomcat/webapps/draw/js/PreConfig.js: Permission denied
/docker-entrypoint.sh: line 17: /usr/local/tomcat/webapps/draw/js/PreConfig.js: Permission denied
Init PreConfig.js
/docker-entrypoint.sh: line 18: /usr/local/tomcat/webapps/draw/js/PreConfig.js: Permission denied
/docker-entrypoint.sh: line 20: /usr/local/tomcat/webapps/draw/js/PreConfig.js: Permission denied

I left the user/group config of the container at the default (568/568).
Seams like these errors could be part of the https-problem. Is there anything I can do to get ride of the problems? Do I need any other tweaks to make drawio work with https?

Thanks!