Find the max value from your number series and enter the same in text box and after click on the button.
Suppose 5.7 is the max value from this numbers ( 1.34, 0.45, 5.67, 4.4, 5.7, 1.3, 4.5, 1.34, 0.45, 5.67, 4.4, 5.7, 1.3, 4.5, 1.34, 0.45, 5.67, 4.4, 5.7, 1.3, 4.5, 1.34, 0.45, 5.67, 4.4).
Here you'll get the StepValue/YAxis major value by using the screen action. Please pass the same value in YAxisFormat's Max Value of Outsystems Graph and you will get Y Axis same as Excel.