At this time, the stock browser doesn’t support Volume button for scrolling. If this is an important feature for you, here’s a list of 3rd party browsers that let you set the Volume button for scrolling.

1. One browser.
2. Dolphin.
3. Baidu broswer.
4. UC browser.

Alternatively, you can enable Air View (List scrolling) on your Galaxy Note 4 which lets you effortlessly scroll up or down in the stock Internet browser by holding the stylus over the edge of the screen.