Two things:
1. Make sure `.PY` is in `PATHEXT` (Python 3.7 installer should have done that for you);
2. Make sure `$ChocolateyInstall\lib\googler\tools\` is in `PATH` (the googler installer script should have done that for you). Restart whatever terminal you were using. You may need to close all open "terminals" (again, whichever one) first for the environment variable change to take effect.