Editing text/change pictures on ipad pro

Just received an email for combining project files and drag and drop to arrange pdf pages.  I just listened to the video and it says you can save to the cloud and make changes from your ipad anywhere.  I tried to do this and not able to.  I have Adobe Reader installed on my Ipad Pro and wanted to add/delete text to a saved document.  When I select the T tool and click where I want to make the change it brings up a text box and unable to insert/delete the text I want to change in the sentence.