File Preview Error: Can't use different PDF URLs

Here is the code. I have tried several other PDF urls and none work except for the sample Adobe ones. I am 100% sure I am overthinking and there is a very basic step which I am missing, but can't figure it out. 

<div id="adobe-dc-view"></div>
<script src="https://documentcloud.adobe.com/view-sdk/main.js"></script>
<script type="text/javascript">
	document.addEventListener("adobe_dc_view_sdk.ready", function(){ 
		var adobeDCView = new AdobeDC.View({clientId: "<YOUR_CLIENT_ID>", divId: "adobe-dc-view"});
		adobeDCView.previewFile({
			content:{location: {url: "https://www.nature.com/articles/s41586-021-04116-8.pdf"}},
			metaData:{fileName: "s41586-021-04116-8.pdf"}
		}, {});
	});
</script>

I have seen different posts similar to this, but none of the answers were clear/helpful in my case.