Take a look through this thread: 2D lighting in Defold(SOLVED)
[Edit] I got ninja’d (so I ninja back). 
Drawing to the render target, and drawing the render target to the screen are two separate things, you want to use different view and project matrices to draw the render target to the screen (an orthographic projection, presumably). Usually you set the view matrix to “nothing” (an identity matrix), and the project to an orthographic one that makes your quad with the render target on it fill the whole window. This is discussed in the thread I linked as well.