As stated in the installation instructions, System Workbench for STM32 version 2 can only be installed on an Eclipse versions being at least Mars... The Kepler version is not compatible as it miss a few features needed for the debugger to run.
So you have two possibilities:
- Install a more recenbt version of Eclipse (avoid Oxygen however, as there seems to be a few problems with this latest erlease; the best is probably to install the Neon release) and install into Eclipse as you are used to be
- Download the all-in-one installer, then, if needed, install the other plugins you may need.
Hope this helps,