Took me a while to figure out what I was supposed to do with the arrows (even after reading the instructions). It really wasn't clear to me what "box" you were talking about, I though it meant the thing to the right of the trash can. I think this issue could've been fixed by something quite simple, like making the two arrows the same color (again, this was confusing for me as the red/green combo is usually for selected/not selected or activate/cancel type of stuff) and putting an outline of the same color or a background of the muted version of color in the box, or there's probably better ideas than what I came up with while writing this.
Also, the incomplete roads were again quite confusing to me, although this took only a few short tries to understand. Maybe a little outline on the sides and none on the end to show that they're not dead-ends.
So, all in all, my main critique is about giving the right visual cues to make the game speak for itself intuitively. With that nailed down, very few instructions would be necessary, guessing how it works could even be part of the fun.
(Of course, I completely understand you didn't have time to polish any of that, I still thought I'd say it because feedback is good.)
That being said, I do like the concept and the general aesthetic you got going on. You could easily elaborate on what you've already got by adding new mechanics in later levels and have a solid puzzle game that isn't repetitive and gets progressively more challenging. The drag and drop mechanic didn't bother me that much, a way to make it less tedious could be to center the boxes you drag from (instead of being in a corner) so the movements you have to make with your mouse/trackpad are shorter. And adding a right-click to delete function or something.