Enable touchpad scroll button on Fujitsu S752

I have a Fujitsu Lifebook S752 and it's got a nice up-down button for scrolling located between LMB and RMB on the touchpad. It did not work on Ubuntu 20.10 and neither on 21.04. It works fine in Windows.

I am not sure if it is due to the driver or the buttons not being mapped. From my testing they don't do anything.

I have no experience toying with drivers or button mapping, so I have no idea where to start.

Any pointers please?

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