• clone the project
• open doc.tex in a tex editor (e.g. TexStudio)
• edit variables.tex
• include content
• export it as a PDF/A document
• sign the pdf using a digital certificate and appropriate tool

This is free and unencumbered software released into the public domain.

Anyone is free to copy, modify, publish, use, compile, sell, or distribute this software, either in source code form or as a compiled binary, for any purpose, commercial or non-commercial, and by any means.