by Ken Task.
Not a Windows person ... but ...
look at the backup.php script itself ... all cli only scripts have require lines:
In backup.php
require(__DIR__.'/../../config.php');
Scripts will use variables found in config.php ... like DB Driver.
Is c:\bitnami\moodle-3.11.2-0\php\php.exe the same as php-cli or is it the same php that runs the web?
'SoS', Ken