The Edit PDF feature is only available on iPad to subscribers to Acrobat Pro DC. iPad users have access to the new Edit Text feature which provides some of the same features found in the desktop version of Acrobat. This feature allows you to:
Add and delete text
Change font styles
Move and Delete paragraphs
Undo and redo actions
Sign-in with the Adobe ID and password which is associated with the subscription of Acrobat in Adobe Reader application on your iPad.