Python markdown not getting variables values

I want to render a notebook to pdf and use some dynamic text, but I have some issues...
This is what I write:

This is how it looks when I execute the markdown cell:

The metadata in the markdown cell looks like this and I can't edit it:

And when I export to pdf or html, I don't get the value of the variables, just the entire syntax --> "{{variable}}"

Any help or suggestions? I'm new and learning to use Jupyter Notebook, not happy so far :(