Hey guys, I did a fresh install on my local machine and configured everything like I should by following the instructions. It worked. Then I checked all every config file and right now I have the same config files on both machines. Still the problem exists.
When I change the httpd-prefix.conf to force the app to use https (RequestHeader set X_FORWARDED_PROTO 'https') he will use https only and the site is SSL secured. But it doenst show the Login site (domain/login, which is only accessable without https) but only the "Awesome! RedmineCRM + Agile is now installed." page. When typing /login behind that manually it still says The requested URL /login/ was not found on this server.
So the problem remains. /login is only accessable via http. When using https it shows the Redmine landing page.