У вашего броузера проблема в совместимости с HTML5
An easy fix for Razer Deathadder 3.5G and older 5 button mice, when Razer Synapse is crap and doesn't work for you.
I've tried using the older DeathAdder legacy driver that worked for a while but has recently stopped working again.
I flicked the bloke a few bucks to say thanks for making the driver freely available, it saved me buying a new mouse in frustration.
X-mouse button control link:
https://www.highrez.co.uk/downloads/xmousebuttoncontrol.htm