Downloads of Padauk include the necessary Graphite smarts to render the Myanmar script correctly.
Thus if you want to use this font at full fidelity to the orthography, you will need to use Graphite-capable applications, such as the latest versions of LibreOffice.
However the web font files served by Google Fonts do not include Graphite tables.
Fortunately, Padauk also has OpenType tables which allow it to be rendered in a basic way, in applications that support OpenType shaping such as Word.
The web font files served by Google Fonts include the OpenType tables, so the font will work in most web browsers.