I have multiple Macs, run a full Mathematica on one, and am trying to use the free Wolfram Player on another. Wolfram Player is installed and is version 12.1--the latest. See https://www.wolfram.com/player/. One of the feature bullets for Wolfram Player is "Explore thousands of free applications from the Wolfram Demonstrations Project and other open-source resources"
As the first trial, I open Wolfram Player and click on the 2nd of 3 icons called Interactive Demonstrations. That opens a window in my browser, switching me away from Wolfram Player. The URL it takes me to is
Now if I click on a specific demonstration, it runs (slowly) in the browser not the player. There is a big Download button on that page and I can download the demonstration notebook to my Mac.
Now when I double-click, it opens in Wolfram Player, but Wolfram Player puts up a dialog box with "You are running in a mode which does not allow this kind of file to be opened. Contact Wolfram Research (http://www.wolfram.com) about enabling additional capabilities."
The documentation for Wolfram Player says "You can now take your notebooks with you and play them offline. Wolfram Player supports notebooks running interfaces backed by Version 11.1 of the Wolfram Language—an 11.2 release will come shortly. Wolfram Player includes the same kernel that you would find in any desktop or cloud release of the Wolfram Language. ... Once installed, you’ll be able to view any notebook or Computable Document Format (CDF) file, including ones with dynamic content."
What am I missing or doing wrong?