Best way to load Javascript into a page

I have a requirement to integrate maps using the OpenLayers3 library. Their quick start example is here:

https://openlayers.org/en/latest/doc/quickstart.html

I've tried putting some of this example into an HTMLSnippet widget on a page but nothing is happening. I've checked the Network tab in Internet Explorer and it doesn't look like the open layers javascript is even being imported in.

Does anyone have an example they can share where they have successfully integrated a third party javascript library into their app?