Did you really mean to run InDesign Server? It has no typical user interface and is used for automation.
Thanks for replying. I did not mean to download the server, but that was what I got after I clicked "Testversion herunterladen". Now I figured out that that was the wrong way/file.
What you need to download is the "Creative Cloud Setup.exe" which installs "Adobe Creative Cloud" which lets you install the InDesign App.