I have exactly the same error if I try on Windows 64 bit, build a “win32” build"
running build_apps
Building platforms: win32
Gathering wheels for platform: win32
Looking in indexes: https://pypi.org/simple, https://archive.panda3d.org/simple/opt, https://archive.panda3d.org/thirdparty
Collecting panda3d (from -r C:\Panda3D-1.10.6-x64\samples\asteroids\requirements.txt (line 1))
File was already downloaded c:\panda3d-1.10.6-x64\samples\asteroids\build\__whl_cache__\win32_cp37m\panda3d-1.10.6+opt-cp37-cp37m-win32.whl
Successfully downloaded panda3d
WARNING: You are using pip version 19.2.3, however version 20.0.2 is available.
You should consider upgrading via the 'python -m pip install --upgrade pip' command.
Building runtime for platform: win32
There are some missing modules: ['__builtin__', '_posixsubprocess']
warning: build_apps: could not find dependency VERSION.dll (referenced by python37.dll)
warning: build_apps: could not find dependency VCRUNTIME140.dll (referenced by python37.dll)
warning: build_apps: could not find dependency VCRUNTIME140.dll (referenced by deploy-stubw.exe)
warning: build_apps: could not find dependency SETUPAPI.dll (referenced by libpanda.dll)
warning: build_apps: could not find dependency bcrypt.dll (referenced by libcrypto-1_1.dll)
Copying game files for platform: win32
Writing /c/Panda3D-1.10.6-x64/samples/asteroids/build/win32/models/plane.egg.bam
C:\Panda3D-1.10.6-x64\samples\asteroids>
The conclusion is simple, you can’t be on a 64-bit system and build a 32-bit build in reverse too.