I converted my rectangle into a curve so that the array can follow the path, but as you can see in the picture it's trying to smooth the edges. I already applied scale, location and rotation for the curve and the array, but it didn't solve the problem. I don't have any unapplied modifiers on my curve.
File: https://drive.google.com/open?id=1c2ogiodGyhzVrWPXdxHMtTJrR9jsoBaK