I went to the blog post you linked and followed the link they had as well (Media Map). If you sign in to ArcGIS Online > choose "Create a Web App" > add a title, tags and choose your map > on the Configuration page under the General tab there is an option to "Find current location". Once you enable this option, save your changes and launch the app you should be able too see it. Please see the screenshots below for more detail.
Hi @SaraESS thanks for the quick response.
Unfortunately I am not seeing the same thing you are. There is no "General" tab in the builder.
I have created the app from the configurable apps gallery (new JS 4.X framework app)
When opened there is no general tab or way to add the Current Location Widget from either the Express Builder or Advanced Builder-