Login Error after installation

Hello all,

i have installed Pentaho CE 5.2 from http://community.pentaho.com/ on Windows 8 using Java 7. I have set the PENTAHO_JAVA_HOME variable.
When accessing http://localhost:8080/ when trying to Login with "Admin" and "passwort" i always get a Logine error message.

Did i miss a installation step?
Any idea how to fix this?
Where can i find an official install document for community edition?


Thanks for your help!

David