How to list academic courses and grades on a pdf form?
The two easiest approaches to this are:


Most PDF viewers have a "typewriter" tool that you can use to write on the document.  For example, the built-in Preview application on Macs has an "add text" tool for writing on the document.  It won't turn the PDF into the form, but you can just write the text where you'd write if it was a form.
As noted in the comments: print, write, and scan/photograph.