In other words, Adobe Reader won't let you add text. What you need is a program that's a little more accommodating, PDF-wise. Try Foxit Reader 4.3, which allows you to add text to any PDF.

That said, free users can make certain changes to PDF files without a paid plan. As a free user, you can add comments, highlight sections, draw on a document, add new text, and sign documents.

Microsoft Edge provides a feature to highlight text in PDF and save highlighted PDF to your PC. This post shows you how to to highlight and save PDF using Edge.