print file in booklet form to PDF for Mac?

Running Mac 10.11, Adobe Acrobat PRO DC

I have a file I want to print in booklet form, but to a pdf file, so I can send to a colleague for the actual printing.

Pro DC doesn't allow me to print in booklet form to a PDF file, saying I have to click File/Save. Why not? Is there something I'm doing wrong?

Can it do what I want it to?

please advise

thanks