Automate 400 Creator Agreements

I need a reusable automation that turns a single Google Docs agreement template into about 400 personalised contracts—one for each creator listed in my Google Sheet.

Here is the exact workflow I want the script to handle:
• Read every row in the Google Sheet, pulling the creator’s name, address, PAN and (when present) GST number.
• Make a fresh copy of my Google Docs template for that creator.
• Replace the name on both the first and last page, insert the address, PAN and, if available, the GST number, leaving the GST field blank when the sheet shows none.
• Save the document in my Drive (or a shared team folder) with the file name pattern “<Creator Name> - <PAN>”.

A Google Apps Script seems ideal because it sits inside Drive, but I’m open to lightweight JavaScript that achieves the same end-to-end result within Google Workspace. The final deliverable should include:
1. The working script with clear in-line comments.
2. A brief setup guide so I can authorise and run it myself.
3. One sample generated agreement that proves the placeholders swap correctly and the file is renamed as specified.

If you have existing snippets or add-on experience with Apps Script, Mail Merge-style add-ons or any similar workflow, let me know—speed and reliability matter more than a flashy UI.