REST_FRAMEWORK = {
    'DEFAULT_PERMISSION_CLASSES': (
        'rest_framework.permissions.IsAuthenticated',
        'rest_framework.permissions.AllowAny',
    ),
    'DEFAULT_AUTHENTICATION_CLASSES': (
        'rest_framework.authentication.BasicAuthentication',
        'rest_framework.authentication.SessionAuthentication',
        'rest_framework.authentication.TokenAuthentication',
    )
}

class ClientsAPIView(APIView):
    permissin_classes = (
        AllowAny,  # Or anon users can't register
    )
    def post(self,  request,format=None):
        post = request.POST
        try:
            user = Client.objects.create_user(post['email'],post['password'])
        except IntegrityError:
            return Response({'error':'blalala'})
        serializer = ClientSerializer(user)
        return Response(serializer.data)

{"detail":"Authentication credentials were not provided."}