Trying to link from one product/category to another – Get URL gives me "Non"

Hi everyone. Thank you for looking into this.

I haven’t gotten any responses so far. Maybe my description was too long.
Here’s the drastically shortened version.

Why is it that I can’t link back to a related category? “None” is the only choice I’m given in “Get URL”.

You may want to look at the attached screenshot and the read-only link to understand.

I hope someone can help! Thank you!

Here is my site Read-Only: