I have a PDF file that I need to add editable fields to. However, I don't have Adobe Acrobat, which costs money. Is there a free app out there that will let me do the same?
LibreOffice will let you create PDF forms.
When exporting, go to "Export as PDF..." and make sure you tick "Create PDF form". If you are changing an existing PDF, then you can do that through the PDF import extension/plugin (that's now already included with the latest download).