New Installation: Empty Page after login

Hi, I installed Aras Innovator 11 SP9 on a blank server. Installation went through without any problems. I also get the login windows when accessing Innovator. However, after I entered the admin credentials, I only get an empty page with only the "aras Innovator" logo in the top left and the "Logout" link in the top right corner and a button that say "Hide" when hovering in the left colum. The rest of the page is just white. I tried reinstalling, but no change. I also tried multiple clients (Internet Explorer, Chrome, Edge). Any ideas what I'm doing wrong? Benno