OK, you’re part way there. The XML is never turned into a file, it’s just returned to HelpSpot. The XML file on the Live Lookup page is just a sample of what your script needs to produce if you’re writing the script yourself.
Also the CSV file must be in the exact format specified in the php file. That could be where your problem is. Generally it’s best to interact directly with your database and skip the CSV file because it eliminates the need to keep the CSV file up to date, but it does work if you have to use CSV.
It’s best to start by manually checking if the script is retrieving results from the CSV file. To do this from the browser go to the bbw-livelookup.php script in the browser and manually pass in information which is known to be in the CSV file.
bbw-livelookup.php?customer_id=CUSTOMER ID HERE
Your browser should show XML returned from the script. If it doesn’t then the script probably isn’t able to read your CSV file. Tinker with things until it’s working.
Once you get it working manually try from HelpSpot and it should work. If not you can check the error log in Admin->Tools->Error Log for any errors.