Ren'Py depends on a number of Python modules written in Cython and C. For changes to Ren'Py that only involve Python modules, you can use the modules found in the latest nightly build. Otherwise, ...
You must set renpyWarp.sdkPath to a directory where the Ren'Py SDK can be found. If you haven't done so, a prompt will appear to inform you to set it. Try and keep both in sync with each other.