EDIT:: I found an alternative way of configuring stylus buttons if Ubuntu settings refuse to show the settings. The way is described here, in the "Wacom tablet" section: https://www.davidrevoy.com/article316/ubuntu-16-04-for-my-digital-painting-workstation
I'm using Ubuntu 18.04, installed it on a clean HDD 5 days ago. I've just plugged in my Wacom tablet - which is Wacom Bamboo CTL-470, and it worked instantly - stylus moves the mouse around, applications can read pressure, and stylus's touching and both buttons are mapped to left, middle and right mouse button.
In system settings>Devices>Wacom Tablet, "Tablet" page works, but "Stylus" page doesn't - it says "No stylus found" no matter what - and yes, I did hover my stylus over the tablet - even tried holding it above the tablet while rebooting, and on bootup it still didn't find it.
I'd like to rebind one of the buttons to CTRL+Z, but with it not detecting the stylus it doesn't want to show me the settings.
Any attempts to look up this problem on the internet resulted only in me finding solutions for the problem when that tablet doesn't work completely, and for older versions of Ubuntu.