Docker Dev Installation Don't Work

Hey guys!

I’m trying to try out the application using thedocker-compose file for development, located in

All containers are initialized and stand.

However, when accessing the page localhost:8081 and trying to login with the credentials provided in the tutorial ( / adminadmin) I get the following error:
*Sorry, there was an error connecting to the server"

The browser console reports the following errors:

I believe this docker-compose-dev.yml needs some tweaking or am I doing something wrong?