You reach Kibana under the "COYO_LOGGING_URL=" value in the .env file.

Check in Kibana:
Settings -> Indices under "Index name or pattern"  the following has to be entered:
coyo-*

Then click on "Create".

Afterwards it is possible to see all log messages under Discover. 
In the upper right corner you can also set the time frame, which will be displayed and possibly searched.