Your tablet may not be working on recent a Mac OS computer due to security settings. Recent Mac OS versions added many security features to keep the computer safe from applications not downloaded directly from the App store. If an app is downloaded from the internet or directly from a developer, i.e. the Wacom Driver, the OS continues to protect the Mac. These added protections require additional security settings to be adjusted.
Until these settings are accepted, the tablet functions such as the Pen and touch input will not work correctly.
Below are links to our guides to install the driver and what security settings need to be selected. Please uninstall your driver and follow the steps.
There is no driver support for 10.12 or newer with the Wacom Intuos 3. The last driver for the Intuos 3 can be located here.