For this example I downloaded the Philippines KMZ level 3 file from here: https://gadm.org/download_country_v3.html
I used 7-Zip to extract the gadm36_PHL_3.kml file to produce gadm36_PHL_3.kml.
On line 3 of parse.php - The level I want to generate (based on the KML level):
$level = 3;
On line 4 of parse.php - The first part of the filename you want to parse
$file_part = 'gadm36_PHL_';
This will parse the entries of gadm36_PHL_3.kml into the cords_3 directory structure in this repo.