Right-click technically "alt(ernative)-click", for me it's "left-click" and part of the reason for this guide, but I'm gonna go with the conventional name for the sake of not confusing readers the game entry in the Steam client. Then left-click on "Properties..."



On the "General" tab of the opened window enter "-sysmouse" (without the "") in the box at the bottom, under "Advanced users may choose to enter modifications to their launch options."

Close the window, changes made are automatically saved.

Now the game uses the mouse settings you made in the Windows mouse options (or even mouse properties), like primary button aka left- or right-handed setting, or pointer speed.