If you have Templafy installed locally on your computer, just open your Office application (Word, PowerPoint, Excel etc) and navigate to Templafy's customized tab, then open the template you wish to use. The below images show what this will look like.
Available libraries: Presentations, Slides, Slide elements, Images and DAM integrations
Available libraries: Documents, Text elements, Images and DAM integrations
Available library: Spreadsheets.