So it sounds like you are using on prem install? Our cloud based one is the simplest setup for trying out detection engine if you're just getting your started and want to play with it as it doesn't really require much setup to be honest. 
However, if you want to setup and run on prem following this set of steps is the simplest:
If you have already followed those steps but are still getting the same screen and just want more in depth trouble shooting because maybe you have a really involved on prem large custom setup and you're one of those in-depth geeky type of people you can open your dev tools from Chrome and look for this in your network tab :
You can then see which part of the trouble shooting guide is still not satisfied. There have been some rare reports of large installations of on prem or corner cases involving reverse proxies that have been preventing detection engine from running but those have been rare and far inbetween. Most of the times it's just something missing from the checklist listed on our website.