Having trouble converting fillable pdf to non-fillable on MacBook Pro.

You did not read between the lines.

"Adobe softwares are limited…" : you can open the PDF with Apple-Preview (or any PDF viewer) and print as PDF.

Thanks for the responses.  I don't have the option in the Adobe software when I select print, to print to pdf.   So, I ended up sending it to a staff member who has a PC and she did it by choosing  Optimize PDF, then  discard objects, then flatten form fields.  then she sent to me, I uploaded it to the court website and they accepted it.

I think I have those same options on the Adobe software I'm running but I wasn't brave enough to play around with it like she was,

Use a script to make fields read only and set the default value of the field to the value of the field. The last step will keep the current value if the form should ever be reset.

Adobe softwares are limited to not being able to use MacOS PDF Services and there are good reasons for that (which have nothing to do with flattening).

Refrying PDFs: the Good, the Bad and the Ugly : http://abracadabrapdf.net/file/Refrying_PDF.pdf

On MacOS you can "print to PDF" with any software, except those from Adobe.

The PDF Printer is only available on Windows machines.

Regardless, you need to ask them what they mean by "flattened". It can mean at least three different things in the PDF world and if you use the wrong one they'll probably reject your application.

Read this:

Lock Buttons in Adobe DC