Once you've downloaded the installer, double click it to start the installation.
You will then be taken to the first page below
Click next on this page to go to the license agreement page
After accepting and clicking Next you'll be able to select the destination folder
Here, you can change the default installation folder if you wish, and click Next, you will see the following page, where you can select the start menu folder that LoadUI will appear in.
Clicking Next will begin the installation of LoadUI
Finally, once the JavaFX runtime is finished installing, you will see the final installation screen
Now you are ready to use LoadUI!