ESRI's example code for JS API is not working. Any clue why? (CodePen included)

[GeoDev]

CODE: https://codepen.io/ggii/pen/JjNQBYx

TUTORIAL: https://developers.arcgis.com/javascript/latest/add-a-feature-layer/

The code is from these examples. I cannot get any of the FeatureLayer's to show up on the map. They should be hiking trails and icons. I copied and pasted their exact code. Any clue why?

[RobertScheitlin__GISP · Accepted solution]

@GeoDev , Because you have not inserted your API Key into your codepen code.

https://developers.arcgis.com/documentation/mapping-apis-and-services/security/#api-keys

[GeoDev]

Thank you!