Sometimes it really pays off to read the manual, which states you should publish the example site before you can request anything (since for starters the DXA web application configuration needs to be published from the CMS, the HTML design needs to be published from the CMS, and the homepage and its includes also need to be published, else there is no page to request), and if for whatever reason you don't want to publish the entire example publication, it even specifies exactly which pages you have to publish before you can request the homepage;
To publish the minimal set of items, select and publish the following Pages:
Home/_System/Publish HTML Design
Home/_Error Page Not Found
As can be found here in the online docs: http://docs.sdl.com/LiveContent/content/en-US/SDL%20DXA-v4/GUID-626FDF93-2D0B-4B3B-9CB1-9A0D7402FD82
So I think the reminder here should be read the manual, we didn't spend 20% of our developer budget on documentation just because it was fun...