First make sure that the problem is really PyPy, it might just be that you cannot compile any source package on your machine (someone reported that problem on the pypy issue tracker but it turns out not to be a PyPy-specific problem)
Can you use your build environment? You should have a start menu item about "VS2019 ... Command Prompt", and after opening that you should be able to run the compiler cl /?
. If you cannot run the compiler you may have installed the tools without actually installing a c/c++ compiler.
Can you create a virtualenv with cpython3.6 (not PyPy) and make sure pip install --force-reinstall --no-binary :all: numpy==1.17.0
works on cpython3.6 on your machine?
Does pip install --upgrade setuptools
change anything?
Can you install something else that should build a c-extension module, like lxml (pip install --force-reinstall --no-binary :all: lxml
)?