Prerequisites:
Woffice theme version 4.0.4 and above
Steps:
Access the Addons section here: https://woffice.io/downloads/advanced-tasks-for-woffice/ , purchase and download the plugin
Navigate to the Plugins > Add New section
Upload the file within the Uploads section
Activate the plugin
Add your license within the Appearance > Theme Settings > Plugins > Advanced Tasks For WOffice and activate it.