Difference between oracle database desktop and server class
May the reason be why I installed Oracle as desktop class instead of server class?


No, 'Desktop Class' just means you only get basic choices from the installer1, according to the docs:


  
  Desktop Class—This installation class is most appropriate for laptop or desktop computers. It includes a starter database and
  requires minimal configuration.
  Server Class—This installation class is for servers, such as you would find in a data center, or used to support enterprise-level
  applications. Choose this installation class if you need access to
  advanced configuration options.
  
  
  During a Desktop Class installation, you make only basic choices. For
  a Server Class installation, you choose either typical installation
  (where you make only basic choices) or advanced installation.
  
  During a Desktop Class or a typical installation, Oracle Database
  automatically installs the sample schemas.


You'll need to go through the kind of troubleshooting steps suggested in the comments to find out what is causing the ORA-12545 error:


  An ORA-12545 error occurs when the client is not able to contact the
  listener on the node specified. For example: when the listener has not
  been started on the node, if the node address has been specified
  incorrectly, or a firewall blocks access.




1 So 'Desktop Class' and 'Server Class' are poor names for the installation types. 'Basic' and 'Custom' might be better?