No. You only need to be online to use Templafy web app. From the Templafy web app you have access to all your company templates.
However, if you want to integrate Templafy in MS Office applications, then you need to install the Templafy Add-ins.
The add-ins gives you direct access to templates, images and all other content directly in the applications were you work.
For more info about the Templafy add-ins click here.