The current ndt_map_publisher node expects the PCD format to contain at least fields X, Y, Z, and INTENSITY (which must be of type float or uint8_t). This is why your custom map did not load.
As for why the AutonomouStuff Parking Lot map did not load, it is probably because this file is checked in to the AutowareAuto repository with git lfs which does not pull the file automatically with a simple git clone. In order to pull this (and all other git lfs files), cd into your AutowareAuto folder and run:
sudo apt install -y git-lfs

After this, re-build the autoware_demos package and it should then be able to load the example PCD.