The date drop down box does not appear as an option in the Prepare Form program. How do I add this so I may use with a field?

My program subscription was purchased in December 2017.

This feature is not yet included in the perpetual version (2015) of Acrobat Pro DC, it will probably be in the next update.

As Thom said it's a "fake" tool: a text form field with a presettled Date format, anyway end users don't care since this feature is included in Acrobat Reader DC.

Acrobat DC provides a Calendar field. However this field is actually a regular text field with "Date" formatting. It's nothing special. Nothing different from form fields with date formatting in any version of Acrobat. The calendar drop down is a feature of Acrobat DC, not of the PDF. Any PDF with a date formatted form field will display the drop down in Acrobat/Reader DC.

What version of Adobe Acrobat do you use?

What icons can you see on the Prepare Forms header?