the gaze point values should be normalized over your screen area (0,0) represents top left corner and (1,1) is the bottom right corner. To get correct values you need to have done a correct screen setup. You typically don’t have to do this yourself if the tracker is a consumer tracker such as 4C or ET5. Once you get correct coordinates you need to multiply the values with the screen width/height in pixels if that is what you need. With the defailt license I acutally think you can’t change the screen setup. Use the tools that comes with the eye tracker for this.
User calibration is not really related to this problem, but to get correct gaze data you also need to make sure your user is correctly calibrated. Again, this isn’t something you have to (or can) implement yourself for consumer devices.